Okay so I've been an anime fan for a over a decade now (I'm too lazy to truly work this out exactly plus "anime" wasn't a word until over a decade ago) and this take a look at fangirls.
Girls do it Worst
Hate to say it, but having been an anime fan for this long, I'm going to throw my fellow fangirls of anime at being worst then the boys at being a fangirl. The biggest most apparent mistake for a fangirl to make is calling everyone "chan" or "sama", you try stopping them and BOY do they kick up a stink. The thing is, these titles are like Mr, Miss and Mrs, used the wrong one and you get funny faces at you. And so using "chan" for everyone who is a girl might now always be a good thing (boys can carry it too) and there are other titles for young females, same with "sama". The only time I myself ever used a title was for Beholder, who told us to call him "Beholder-Sama".
And thats not the only word, it took me five years to stop saying Kawaii after I picked it up from anime fan girls. 5 years?!?!? Call it "cute" and have it at that, don't use Kawaii for the sake of it, it actually makes half the fan girls sound retarded when they use it. Not because its being used, but just because they use it for the sake of using it. "Cute" is not only easier to say, but easier to spell. In the last half a decade "Desu" crops up a lot (I forget what this means) but they just use the word again randomly. "Baka" we all know means "idiot" but there are other words as well to use.
Japanese fans of anime actually DO mock English fans that use it randomly. Mostly because THEY know you're using it WRONG. Just because a Japanese person may describe the thing with that word, doesn't mean you should try to use it yourself, because you're not Japanese and don't know fully what your doing with the word when you throw it in randomly. Go to Nicovideos, you'll fine videos of Japanese fans mocking English ones. Besides its not like theres not English words out there for the same meaning as it is. Its not like an English speaker using Déjà vu (French) because there isn't an English proper word for it, or a Frenchman using "La Weekend" because originally there wasn't a word for the Weekend. There are some exceptions to using Japanese words, "Damashii" for example, is okay to use because "spirit" is only a rough translation at best. But why would you use this word I don't know since its not really useful in every day messages?
And so there is a term here called "Wapanese" which is a mock name for people who many would describe these fangirls. Its like with Cosplaying, you can cosplay, but a Japanese cosplayer isn't the same as a westerner cosplayer. Your doing it for fun, because everyone else is, because of whatever reason... Their doing it because its a cultural statement. And I note Westerners have the "Cos" from costume down to a tee, but forget the "play" on the end of the word. Incidentally as well, a professional cosplayer from the west will often let you photograph them, whereas a Japanese professional is very picky - you MUST let them go to the booths for photographs which means it may cost you money.
Actually why I suddenly talked about cosplaying I don't know... Its another fangirl comparison I guess. Oh that reminds me of one more thing: Names!
Sonic is "Sonic the Hedgehog" even in Japan. Soniku is just how they say it, because the "c" at the end isn't transferable without adding one extra letter on the end. Fangirls often insist on using "Soniku" instead of "Sonic" because as he came from Japan they believe its correct... But then again "Super Sonic" is "Supa Soniku". I'll never understand the logic behind this little thing anyway, its not JUST Sonic who gets the treatment. Sometimes it happens in many animes that one or two characters get this treatment. I guess OPs main one is "Oars". Even now people still use "Oz" and "Odz".
Then finally Yaoi and the other variations. I laugh at many Yaoi fans, not just because of their shipping, but because I had Beholder-Sama explain to me once the culture behind Yaoi. To worship Yaoi to a westerner is to look trendy and "modern" and because of the teen hormones at getting high at seeing two cute guys get at it. But to a Japanese person, its a statement. The attitude is not the same there towards gayness (hence why OP can get away with Okama-ism) at all. It never had the downright unacceptable reaction that the west had for centuries towards the same sex relationships. Also they fail to acknowledge there are variations from mild (just kissing) to porn, so two guys in one image may get count as a Yaoi image to a Westerner, but in Japan be something like a lemon image (I recall that refers to strong porn or something).
However they have some respect for those trying to learn their language, mostly they find it funny since the average Japanese person has a fair amount of discrimination towards non-Japanese. But they won't mock you completely for trying to learn their language. Half the mock will be just because though you learn the language you DON'T learn how to say it properly, you learn how to speak it in the easiest polite way. That means slang is left out and proper explanation as to which titles you must learn when saying a person's name are barely touched upon. So what you end up learning yourself is the language that puts you on the level of an 5-8 year old child (oh dear!).
The Japanese themselves use English words, but it to themselves makes phrases sound cooler. Speaking a second language was once rated as one of the things that would make you sexier in Japan. Plus English words are easier to market then Japanese ones. You all know the school things, writing fire with the text on fire... well this is what they use it for in that sense. Plus English being the unofficial world language means you can market something in English and sell it almost across the world. Lets look at One Piece, its know as "One Piece" in almost everywhere, so when you start talking about a show called One Piece to a German fan, they snap and know what your talking about. On top of that, every Japanese child learns the basics of English in their early school life (though many forget it or never taker it further) and Japanese business men most often deal with American business men a lot if they try to sell their products abroad. America's a big market after all...
So for the Japanese, using English isn't the same as going around and using "Desu", "Kawaii" and those other random Japanese words fan girls pick up. For them its a bonus for life if you can string a number of sentences together and be understood by an English speaker.
Incidentally even if you learn the language, Westerners often report hearing Japanese school girls and such like mocking them in Japanese on the train - THEY presume you can't understand them. And even if they take it into account you can talk Japanese, they won't care since their not bothered if you overhear them. Japan's individual rep towards foreigners isn't completely great. That is not to say that they are all like this, most its the ignorant ones who love to stereotype, but don't be suprised to hear it. Even the Japanese government acknowledges its own people aren't friendly towards non-Japanese. In manga and anime, they try not to bring up the matter, and thats why half-Japanese kids get accepted easier then real life. The GOOD news is, if you get accepted into the Japan family, you become a point of interest (particularly if you are a kid or teenager at school level) since having a friend who speaks another language is quite useful to them (the Japanese are a very nice set of people in reality despite all this). But if you can't, expect the Japan family to mock you behind your back, or in front of you if they are brave enough.
So in the long run, its better to try to learn the language, but remember you'll never have the 100% respect of the Japanese themselves, then to throw random words in. At least going to language class you'll get the explanation as to HOW to use some of these words and hopefully by the time you come out will have the common sense not to just throw in those words randomly anymore. I did take a few Japanese classes, which leds me to the other thing - learn it young, by the time your 18 it will be hard for you to learn it. If your 14, want to learn it, make yourself learn it while you've still got your youthful memory on your side. As for me, most of the limit stuff I know came from a book... :-/
And advice from many friends of mine on-line over the years - go to Japan, it will open your eyes to reality of what Japan is be it for the better or worst.
And please, don't just pick words off of on-line Japanese fangirls - thats not using the language right!
And a final note
I will acknowledge that at this point, the fangirls have gotten much, much worst in the last decade. Regarding variations of yaoi, when I became a Beyblade fan back in the first half the 00s, people were bothering to categorize Yaoi and other forms of it. Now laziness has settled in and its rare it get the proper category. And Beyblade was one of the biggest contributors towards the push of the yaoi fad amongst fangirl anime fans. And I hate yaoi, which sums up the frills of my beyblade days.
Oh and why do I hate yaoi?
Simple, back then in particular the artists were always putting a ton more effort into the yaoi pictures then the non-yaoi pictures. That meant if you just wanted to find a pretty picture of Kai or Takao, you have to go through the mountain of Yaoi pics... And then only to find one drab and dull image of Kai that made the search so meaningless. Its gotten better and I must confess, the fad for yaoi is long over, now its "yeah thats yaoi - next pic please!". And because long term anime fans on-line have started to get really fed up with the shipping wars over the years.
So part of me hates the fact things have been more neglected, but part of me is relieved that things are getting better in other areas.
Oh, and finally people are getting the act together on "Mary-Sue" fan fictional characters. That was the second horror of the Beyblade days, the female blader who was "perfect" a match for a character.
Third was when the stories couldn't grasp the true personality of a character and the character acted odd for who they are.
And fourth was... Well... Where is the Beyblading?