dump trunks

Loose, thread-bare fabric sagging in the seat of one's shorts that jostles about like one took a dump in their trunks. Occurs mostly to folks with odd-shaped bods and who believe shorts don't need washing as often as other garments. Will usually smell like bus seat and fecal grease in affected region.

"Connor can't get the smell of skid marks out of his mouth since he bit into Perry's filthy dump trunks."