My only animation-related memory of him was one afternoon he was over at my house, and we watched one of Cartoon Network's Acme Hour blocks (you know, when they actually played cartoons years ago, let alone ones that didn't suck).
Friz Freleng's Tweety & Sylvester short MUZZLE TOUGH (1954; arguably the most groan-inducing title in cartoon history) was on, and I never heard a grown man laugh so hard at a cartoon in all my life. This same block had a few Tex Avery shorts as well, but his laughter at this one makes me think of him everytime I watch it.
In particular, it was this scene of Tweety leading Sylvester up the stairs with a grand piano that had him roaring... Obviously he could relate to having to carry something so massive!
I have no idea who animated this scene (except that Sylvester with the piano keys as teeth is definitley by Art Davis), but I think this clip preserves my own memories of Uncle Bill and his sense of humor very nicely.