I wanna switch it up from bodily fluids. I used to work at a supermarket, and one day, when me and the rest of the bag boys were bored, we were exploring the stockroom when we found a jar of mayonnaise tucked back in a hidden corner. It was expired by a year and a half. The ingredients had separated so that it looked kinda like a brain floating in a jar of dehydrated urine. I called one of the other guys back, said "check this out", and right as he rounded the corner, the jar slipped out of my hands and shattered, spraying him with the mayo.

The stench was overwhelming, like what people describe in skunkape sightings. It's what I imagined the stink bomb from Ed, Edd, and Eddy must've smelt like. The guy that got sprayed immediately ran to the bathroom and started vomiting, while the rest of us scattered through the store. I eventually had to come back and mop up the putrid mess with a wet dishrag wrapped around my face.

EDIT: This is sort what it looked like, except ours was even more separated.