The place between a man's scrotum and leg (where the scrotum is always sticking to the leg), usually very sweaty and stinky when one rubs their finger across it.
I stuck my finger in my cheese crease yesterday after taking a jog and the smell almost made me sick.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi