1.An annoying residual goo which clings to the rim of the anus, the origin of which is most likely a foul bout of hellacious diarrhea.
2.Any smeary substance, no matter the origin, which has deposited on, or in the vecinity of the butthole.
3. A person whose behavior may be characterized the same way. Usually this person is not welcomed company.
"I had to throw out some undershorts yesterday before I could do my laundry at my girl's apartment. I had some nasty buttslime that left tracks on my shorts."
"I wish that buttslime Bill would shut the hell up, and leave already."