What's red, green, and smells like shit?
... Red and green shit.
What's red, green, and smells like shit?
... Red and green shit.
Alright listen up, this one is pretty simple. So, the set up asks what is red and green and smells like poop. The punchline answers it with red and green poop. See, it subverts your expectation by repeating the words from the question to create the answer. You probably don't get many jokes, do you?