"Turn on Your Heartlight" is a song made famous by Neil Diamond. It was inspired by the Steven Spielberg movie E.T. the Extra-Terrestrial. Eric Cartman sings this song to himself while cooking in the Season Fifteen episode, "Ass Burgers".
After hearing from Kyle Broflovski that some people believe vaccinations cause Asperger's Syndrome, Cartman misinterprets this as "Ass Burgers". The next day, Cartman cooks hamburgers before school and stuffs them in his underpants, pretending he has the disorder.