This is a sentence is used by people who are trying to tell other people that they are not gay, but they are gay. So if you say this people automatically going to assume that you like the same gender as you are.
When two men, having a mutual respect for each other, give one another a hug and pat on the back, usually, three times in rapid succession. "pat... pat... pat" which translates to "im... not... gay"
I hadn't seen my friend in so long i hugged him, but i didn't want to seem gay so i have him the "Im not gay" hug.
"TRUST ME MOM IM NOT GAY UGH YOU NEVER BELIVE ME!" this phrase shows you are telling your mom you are not homosexual. Im not gay mom means you are telling your mom that you are not homosexual.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.