This is the week for comic strip cross-overs and cameos. To start, Frazz by Jef Mallett featured an appearance by the cartoon Stephan Pastis. Pastis, the creator of Pearls Before Swine, not only shows up as a character in his own strip, but occasionally pops up in others (Pearls Before Dennis). (click on the image to enlarge)
This sequence is a nice gag by itself, but if you're familiar with the identity of the driver in the third panel -- well, then it's even better.
As I said, there's a lot of cross-pollination going on. I'll be sorting some of it out as the week progresses.