Ziggy: I always bring a little extra money in case there's another postage hike before I get to the window!!

Considering it's appearing in a Ziggy cartoon, this is a very clever joke. It contains two parts. First, it's hilarious because service at the Post Office is slow. Second, it's hilarious because service at the Post Office is expensive. Granted, neither of these potential sources for humor is even remotely original, and at least one of them is rather strikingly false, but for Ziggy it really is an impressive piece of art.

Which is to say, it's not just a piece of shit. It's like two pieces of shit in one.