When John Stamos (Full House, E.R.) joins Glee this season as Emma’s boyfriend, Carl, he’ll be playing a dentist with a musical past – the character was previously in an ‘80s boy band. “Just when Will thinks he’ll win Emma because he can sing and dance, we find out Carl used to be in an ’80s boy band,” Stamos tells TV Guide. Stamos will also reportedly take part in the Halloween episode, which is based on the Rocky Horror Picture Show.