Darren Criss & Katy Perry: 'Teenage Dream' Duet!

Darren Criss and Katy Perry team up for a duet of her hit song, “Teenage Dream” at Trevor Live, which benefited The Trevor Project, on Sunday (December 5) in Los Angeles!

The new Glee star sang an a cappella version of the song with the Warblers before Katy came out and finished the song as a duet with Darren!

“About to do something REAL fun!” Katy tweeted before going onstage.

The Trevor Project is a crisis hotline for LGBTQ youth.

FYI: Darren is wearing a Ben Sherman suit.