My favorite WAC! shorts are as follows:
-"Help!" by Bruno Bozzetto. AFAIK, this was the only foreign short, but who cares what country it came from, it's a riot. The cat has to go through all sorts of unnecessary and unrelated medical tests just to get treatment for pricking his finger. It's a sly satire on health care, when you think about it. The music and animation were both well-done, and I love the production design (such as the literal maze of the hospital).
-"Kitchen Kassanova" by John McIntyre. Loved how the girlfriend kept polishing things while the man was in the kitchen. The Squigglevision-esque animation gave this one a unique look, too.
-"Out and About" by Pat Ventura. Probably the funniest and certainly most zaniest (and that's saying something!) short by Pat Ventura, this Sledgehammer O'Possum short borrows its tone from Tex Avery and runs for miles. Love the wacky saloon-style piano music that plays throughout the short. There's also some creativity to many of the gags.
-"Tales of Worm Paranoia" by Eddie Fitzgerald. Very Ren & Stimpy-esque (thanks to its animation style and stock music), which of course I love. The opening, where the man who's late for work keeps inadvertedly stepping on the worm, is gold simply because the reasons for stomping him are so ridiculous. "Gotta get that exercise!" "Put out that forest fire!"
-"Strange Things" by Mike Wellins. I mainly like this one because it's the only CG WAC! short.
-"Babe, He Calls Me" and "Malcolm and Melvin" by Ralph Bakshi. Worth watching for the wacky animation alone, not to mention the bizarre nature to it all.
-"Larry and Steve" by Seth MacFarlane. Anytime someone calls Seth a hack, I point to this short. It's hilarious, and also proof that he could easily do kids' cartoons if he wanted to, and would do well to boot, as he wouldn't dumb it down for them.
-"The Chicken From Outer Space" by John R. Dilworth. Nails the creepy atmosphere. When I first saw this back then, I was pulled in by the visual nature of it.
-"No Smoking" by David Feiss. Good squash and stretch animation for this Cow & Chicken pilot.
-"Drip Dry Drips" by Jon McClenahan. Displays the same kind of visual charm that StarToons had on Tiny Toons and Animaniacs.
-"Lost Control" by Zac Moncrief. I can't explain why I like this one, I just do. It's visually flat but the short as a whole just seems to work.