A riddle is a statement or question or phrase having a double or veiled meaning, put forth as a puzzle to be solved. Riddles are of two types: enigmas, which are problems generally expressed in metaphorical or allegorical language that require ingenuity and careful thinking for their solution, and conundrums, which are questions relying for their effects on punning in either the question or the answer.
What is invisible and smells like carrots?
The Ether Bunny
Ether, Bunny, Carrots
What did the rabbit say to the carrot?
It's been nice gnawing at you.