the small, whitish (sometimes yellowish or even greenish) in color, foul smelling (completely stanky, really) bits of crumbly clay like crap that come out of the back of your throat when you cough or blow your nose too hard. (See also, tonsil stones)
"Wow Andy, why are you making that disgusted face?"..."Gee Mitch, maybe its because I just hacked up some white poop and I can kinda taste it in the back of my mouth."
When one cums in another's rectum , the recieving party dumps the shitty, cummy load on their partner's chest.
Rich took a giant whitepoop on Jeff's chest after a rousing anal thromp.
That legendary once in a lifetime turd that is white, usually comes later in life.. when u get it, death is imminent.
"Have you gotten the white poop? So young..."