Some of you who are more "hip with the kids" may have already seen this (a couple of years ago, actually). It just makes me laugh every time I see it (yes, I am a bit easily amused), in part because it is the perfect example of the bizarreness, and wonderful-ness, of the internet. Why in the world would such a thing exist? Who would spend that much time making such a thing? (And yet, I'm glad they did...)
(Warning: this may stay in your head for weeks...)
What's your favorite example of an internet item (a flash video, a mashup, or whatever) that is wonderful for its mere existence?