Ditch diaper
Diapers tossed out the windows of cars by traveling families too lazy or too redneck to toss it into a proper waste bin once they've stopped. Eventually, the stinky wad lands into the ditch to keep the roadkill company.
I got run off into the ditch and fell headlong into what must've been a ditch diaper. I thought I'd never get the stink off me.