Recursion

Lather. Rinse. Repeat.

We think the Jargon File defines recursion best:

recursion: n.

      See recursion.

2In order to understand recursion, one must first understand recursion, printed in white on a 100% cotton, dark chocolate t-shirt.

Note: The earliest version of this shirt had a period at the end before we thought better of it. So if you get one with a period, cherish it. Its a limited edition.