You might not believe one of his choices!

Josh Groban is getting ready to belt out a medley of 25 classic TV show theme songs at the Emmys. Is one of your favorite tunes in the mix?

Some of the themes Groban practiced during a Friday rehearsal were "The Golden Girls," "Cops," "The Jeffersons" and even "South Park," with Groban mimicking the cartoon characters' voices, says the Associated Press.

"Nothing I'm singing I've ever sung before, except for 'South Park' with friends," the 27-year-old crooner said. "There's a lot of stuff that allows me to just be me, then there's a lot of stuff that allows me to let my multiple personalities to go play for a bit."

The "60th Primetime Emmy Awards" will be held at the NOKIA Theater in Los Angeles on Sunday, Sept. 21 and will air on ABC at 8 p.m.

And for a second year in a row, ET's post-Emmy bash will be held at the famed Walt Disney Concert Hall, where headliner Billy Idol, and Dave Koz, will rock out for celeb guests like Sean "Diddy" Combs, Christina Applegate, Eva Longoria Parker, Tina Fey, Jeremy Piven, Lauren Conrad, Mark Wahlberg, Marcia Cross, Sandra Oh and Jennifer Love Hewitt.