A musty, foul smelling, creamy discharge, secreted from a felines anus when either frightened or aroused.

Also describes most anal secretions from any animal or human other than fecal matter.
"Johnny, what is that horribe odour?"

"Its ok Pete. I'm just trimming my cats arse and she is scared. It's her Butt Pus".

"Tim!!! What is that smell"? Oh shit I burst a pimple with that last crap I took. I've got Butt Pus!
by Young Skunk October 23, 2011
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