I had never heard of lip dubbing, but these French school kids do a pretty good job on it:

The idea behind lib dubbing is to get a group of people together and make them dub a song, while filming the entire sequence without a single camera cut. In this case the clip is over 6 minutes long, and features students at a technical school in Rouen dubbing Michael Jackson’s Thriller. I bet the rehearsals must have taken days.