Dr. Simon and Mr. Heartthrob is an episode of The Chipmunks series.
Alvin is attempting to win his consecutive title of "Heartthrob of the Year" award. When Alvin is in Simon's lab, he breaks a hair growth formula test tube and attempts to quickly recreate it. Instead of having it grow Simon's hair, it turns him into a heartthrob. Simon likes being Mr. Heartthrob so he tries to drink more. Alvin stops him, taking the heartthrob formula, leaving Simon to believe his hair growth formula is responsible so he makes a vial. Theodore steals the vial from Simon, giving it to Alvin while Simon finds the hearttrob formula in Alvin's spare hat. When they perform, Simon becomes Mr. Hearttrob and a fabulous crooner. Alvin thinks to himself that two can play this game and drinks his formula, but ends up becoming extremely hairy and comes on stage seeming much like a scruffy rocker. After the performance, Alvin loses "Heartthrob of the Year" award, but not to Simon, who suddenly reverts back to his old self and loses because he was not himself. The winner is Theodore! Simon thinks he is a failure as a chemist but is proven wrong when Dave drinks the real hair growth formula.