it all depends on how society interprets the word, and in the case of 'gay' way back when it was probly first used it meant happy.
example: Look all the little skiers having a gay old time.
and that word, gay, used in that manner is also in the song Auld Lang Syne(i think, but its some famous song thats got it), quite famous. so that definition will never be forgotten
then came along the world of homosexuals... i have no idea how or why they chose the word gay to describe their sexual preference but they did.  so now we dropped the meaning happy and adopted 'men fucking in the ass'.
example: Mom, Dad; i heard Timmy talking about telling everyeone hes gay.
Now that definition is still used today, however OUR society, that being the one of people and kids our age, associated the word with people/things/objects/places that we dont like. becuase in fact we were brought up not to like/hate gays. thereforer we adopted that word to represent things we dont like, which also brings in the whole realm of gay-associated words like homo, homosexual, fag, fruit, queer etc... which share that same purpose, of showing dissapproval.
example: Tommy quit being gay.  or  What? are you gay?
so it is all really a progression of society, and if you track back the definatiions and the origons of the word, in this case, gays brought it upon themselves to be made reference to in this way, this deraugetory way.  so in a sense you could say it is their (the homosexuals) fault for all this everyday hatred towards gays.
but really when you call your friend gay, or a fag, you really mean to reference him with a bunch of guys pownding eachother in teh ass??? no, its just societys current word for idiot. and jsut like a fad, if you give it sometime it will most likely fade away.
$$ ICED OUT RACING $$
toss your salad outta here