Above is an extremely unconventionally paced strip, but it works beautifully. Ususally in comedy things aren't done strictly in twos, yet here the action is broken up into two sections, two setups, two frames each. What Watterson demonstrates here is a mastery of Unreal Time. The sense of a tempo is so well conveyed that the strip is free to break the tedious numerical rules of joke-telling.
Cartoons are either superhuman or incompetent. It's not that there's no in-between, it's just that anything that's funny is at least partially one or the other. Calvin's expression above wavers between overconfident showmanship and a willful embrace of his own incompetence - "If she buys it she's an idiot, look at my mouth for chrissakes. If she doesn't, so what? I'm just being an asshole 'cause it's fun!"
Watterson's ability to suddenly draw down and dirty little kid crudeness never ceases to amaze me. His style gravitates toward a very light touch, characters with understated features, a loose yet assured way with ink....in other words, he flirts with the kind of "gentle genius" appeal that Shultz has. But that's just a front - his style strays WILDLY off that course, sometimes out into Scribnerland (or something like it), or into a kind of coarse, MAD Magazine territory where typically downplayed features like lips and nostrils -or even the crease made by buttocks pressed together- are fodder for cartoons.
Watterson loved any expression that involves curling one's lip over the teeth.
Sorry the rest of the strip is missing - basically Calvin looks at his Dad and sees a baby boomer, the cause of all the nostalgic, self-aggrandizing crap he's just been hearing on the oldies' station.
A perennial only-in-Calvin-and-Hobbes moment: comic-strip-as-zoetrope. This is literally nearly-finished full animation. (Well, limited really - but there are subtle changes.)