Comedy Duo Ylvis Make A ‘Foxy’ Surprise Appearance at 2013 iHeartRadio Music Festival

Wendy Geller
Maximum Performance

The opening night of iHeartRadio's 2013 Music Festival solved a few burning questions: How fun. sounds covering a Rolling Stones classic, whether J. Cole and comeback queens TLC are a good match, and just how many hits Elton John can pack into a short set.

However it failed to answer one of the year's most puzzling queries. Namely: What does the fox say?

That's not for lack of trying, however! Norwegian comedic duo Ylvis, who found themselves with a surprise viral hit on their hands courtesy of their silly — and catchy — "The Fox," made an unexpected appearance at the fest…furry costumes, "A-oo-oo-oo-ooo"s and all.

"The Fox," which was intended as a comedic piece by Ylvis's team of two brothers, Vegard and Bård Ylvisåker, was released early in September and caught fire with remarkable speed. The video has received more than 42 million views on YouTube to date, drawing comparisons to the crown jewel of all viral clips — Korean sensation Psy's novelty hit "Gangnam Style."

The 2013 iHeartRadio Music Festival was streamed live from Las Vegas's MGM Grand Garden Arena on Friday, September 20. Headliners included Robin Thicke, Keith Urban, Chris Brown, and Katy Perry. The show continues Saturday the 21st, with Paul McCartney and Justin Timberlake on the bill, among others. Watch it live here starting at 7 pm ET.