I enjoy Keith Knight's comic strip Knight Life. Recently Knight brilliantly pulled together two separate themes, gave them a twist, and came up with a great gag.
The strip references a recent Snickers ad with Joe Pesci and Don Rickles (which I could embed the video, but that wasn't an option -- you'll have to follow the link). In the ad, two men are talking to two women -- as Knight shows in the first panel. One of the men is crabby because he hasn't eaten, and is Joe Pesci playing himself. The man's given a Snickers bar, and turns back into a regular person. So far, Knight's strip parallels the ad.
The commercial ends with the pair returning to the women. But one of them's become crabby and turned into Don Rickles. Knight ends things a different way -- the candy bar had an unexpected effect.
What makes the gag works is the expectation that the strip will follow the ad storyline. The twist at the end provides the humor. But there's something else -- Knight uses comic strip celebrities, and the reader's knowledge of Lucy from "Peanuts" and Broomhilda gives the joke added meaning.
Sometimes cameos in comics don't work very well. But when they do -- as in Knight's strip -- it really makes a comics fan's Sunday.