A term often used to refer to, possibly, the most extroverted gay man you could know. It is preferred not as an insult, rather a more factual description, where any doubt is quickly put to rest.
Some say it originates from co-host Adam on the Nobody Likes Onions podcast, but this is not irrefutable. Other sources suggest it has come from a concept of the original gay, where Adam (as in Adam & Eve) represents the first human male that committed the original sin. Admittedly it's a slightly tenuous spin on the idea of Adam being the original.
My friend is so gay, it's crazy. Everything he does just shouts "Look at me, I am loud and proud.". In fact, he is unequivocally a gay Adam.