I recently had the chance to go uber-meta in a comic strip, all thanks to the word "cochlea" and all of the possible NSFW penis jokes our dirty minds can come up with as a result of how it's pronounced. The highlight for me was also being able to pull the NSFW rug out from under the joke and create possibly the corniest punchline I have ever devised. The level of geekdom is strong in this punchline as well.
Since the joke is merely abusing the word "cochlea", without further ado, here is the punchline:
Cochlea: What did YOU think it was going to be a picture of...hmmm? ;)