People get offended when you use the term "gay" to mean something negative...
...yet those same people use the term "lame".
"Oh, man, that's so lame."
So, I can't use someone's sexual preference in a derogatory manner, but you can mock cripples?
The debate is still out on whether homosexuality is a choice or if people are born that way. But guess what, handicap people don't chose to be that way for sure.
So the next time you are going to throw the phrase "lame" around to be cool around your friends, think twice and call them gay instead.