word of indirect meaning. Having both elements of wiener and dump (poop), the term is used as an insult, but in levity. It is the conflict of not knowing whether it is a wiener dumping (pooping) or a place of discarded wieners that becomes a joke in itself.
James- Do you smell that? *chuckle*
Abdiwak- Oh my- JAMES DID YOU JUST FART?! You're such a wienerdump...
James- *chuckles* Wait. What does that even mean?