It is used as an insult because it was made common from the Jerky Boys phonecalls and movies, but its more of a condition. Sizzlechest is light curly chest hair that appears almost like smoke puffs rising off the chest, little spirily colums of hair. Usually found on assclowns.
A homosexual act performed between usually Greek or black men, which is traditionally noted for the mixture of semen in matted, generally dark chest hair. One homosexual partner will typically don an apron portraying a cartoon penis wearing a chief's hat and shouting from his urethra "kiss the cook!!" The submissive nubian then calls for a deisel load of seminal fluid which he then mixes nuturingly, to shape and condition his chest hair, conforming to the manner and style of today's "afro."
"Hey little buddy, where'd you get that sizzle chest?"
"Tobechukwu just delivered his man-payload...where'd you get yours, the Albanian boy we adopted?"