Dad: Going to the family reunion will be a gay old time.
Teenager: Dad, that's so gay.
Dad: I'm glad to hear you're so happy about it.
Teenager: No, it's lame and boring.
1- Used by people as an adjective to describe things that are retarded, bad, unpleasent.
2- Phrase used in a Politcal Correctness campaign aimed at people not using the phrase.
Gregory-"Did you see that dumb PSA, 'Thats so gay' "
This is often used by straight people who are ingnorant to gays and don't really understand the meaning of what they're saying. Some people take it seriously, while others blow it off. "That's so gay" is another way to say "That's so retarded"