In addition to the bad joke, we have a silent penultimate panel. Matt Gill used to document these at the Silent Penultimate Panel Watch, and he points out the flaws better than I ever will. If you're really interested in comic strips, you should read through his archives. The SPP here adds nothing to the strip and ruins the what timing the joke had.
Runners-up: Blondie, Close to Home, Family Circus, For Better or For Worse, Hagar the Horrible, On the Fastrack, Red and Rover
Runners-up: Candorville, Dennis the Menace, Frazz, Get Fuzzy, Non Sequiter, Pearls Before Swine, Pooch Cafe, Sally Forth