BSLS stands for Ball-Stuck-to-Leg Syndrome. it normally occurs on very hot days, or after extreme workouts, where the sicknasty sweat that builds up glues your ballsack to your leg. it is rather annoying and not at all pleasant.
Jim: Dude, Tim, why are you walkin' funny?
Tim: Dammit man, i got that BSLS. shit.
Jim: That sucks man