The Wikipedia entry for Who's on first - Abbott and Costello's famous baseball routine - is hilarious. It's unclear whether it's intentionally boring (i.e. some kind of deadpan reworking of the joke) or just plain old boring - but the author goes out of his way to kill all fun by explaining the joke:

The names given in the routine for the players at each position are:

* Who: first base
* What: second base
* I Don't Know: third base
* Why: left field
* Because: center field
* Tomorrow: pitcher
* Today: catcher
* I Don't Give a Darn: shortstop

The name of the shortstop is not given until the very end of the routine, and the right fielder is never identified.