lactic brown
When you run so hard your guts turn to liquid acid and you poop your pants like a baby who just saw a horror movie
My sprint class was so intense I pooped my gym shorts and my coach laughed so hard he cried
I did a 400-meter dash and my pants were soaked with lactic brown by the time I got to the locker room
My friend ran a mile and his shorts looked like a science experiment went wrong