I smell up dog in here.
"What's up, dog?"
Nothing much, how about you?
I smell up dog in here.
"What's up, dog?"
Nothing much, how about you?
Listen up, buttercup. This joke is all about "up dog." It sounds like "What's up, dog?" which is a question. The joke is that the first person sets up the second person to ask the question to sound like they are saying "up dog."