The latenight TV version of the 1989 BUAV "Smile" PIF, featuring a more subdued piece of music. ("The Thinner the Air" by the Cocteau Twins, in case you care.)

Evidently, this was done to avoid paying hefty royalties to Charlie Chaplin. I don't think it's quite as disturbing as the original PIF, but it comes pretty close. It does always seems to stick out in my mind, however, probably because of the music. Watching it creates a strange effect, almost like you've been transported into some kind of alternate universe. It's oddly entrancing.