The term refering to girl's pants worn on a guy. The jeans, usually tight and ripped, are probably uncomfortable, but they do give the guy a nice-looking ass.
OMG Tina, did you see those ball crushers?! They're tighter than my jeans!
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