Gettyimages | Dave J Hogan

Robert Downey Jr. revealed during his interview with Howard Stern today that he was actually involved in an altercation, right before his appearance, in the show's green room.

Howard has been broadcasting all day from Los Angeles, after helping launch Sirius/XM's new Los Angeles studio.The day has been packed with huge celebrity interviews including Jimmy Kimmel, Jennifer Aniston, and Arnold Schwarzenegger.