A recursion is an event within a logical/mathematical/programming problem wherein one of the steps leading to a solution includes the steps of the problem itself. Though of great use in computer programming, the more common experience of seeing a recursion is in an image containing an image of the same image. This is like when you're watching a television and you see someone on television watching the same television feed you are seeing. It often happens when you catch a glimpse of a sportscaster or official reviewing playback. The Xzibit Yo Dawg meme is also somewhat recursive, which makes Parkington's joke in the Honda Walking Assist Review hilarious.
Also, jokes about Wes are hilarious.