Gay Men and Cream Filling

Okay, genius, let me break it down for you. You, the author, are probably not the sharpest tool in the shed. This joke uses the word "cocks", which can refer to both a rooster (chicken) and a penis. The punchline plays on the double meaning, suggesting that gay men like penises ('cocks') because of their creamy "filling", in a sexual way. It's wordplay with a sexual twist.