Forget "If You're Happy And You Know It." Songs about pain, heartache and loss appear to be the biggest hits with the under-four-foot-tall set. First, it was "Someone Like You," and really, we didn't think it could get much cuter than babies and kids singing Adele -- until another YouTube trend emerged: kids who know all the words to Gotye's ultra-cool, maddeningly catchy (and vaguely inappropriate?) "Somebody That I Used To Know."
Video produced by Amber Genuske.