Some people say "that's gay" or "you're gay" as an insult to
heterosexual people or other events. If you are one of those people, brace yourself, you're in for a shock.
"Gay" isn't a synonym to: stupid,
weird, uncool,
wrong, sucks, stinks, or any other insult like that.
Saying "that's gay" is basically saying "Look at me! I'm ignorant, insensitive and close-minded!"
The same goes for "retarded"