Peyton Manning is all about his business when he steps out onto the football field. But, behind the scenes, we've heard that he's a pretty funny dude. And he proved it yesterday after working out with a few NFL wide receivers at the 2013 Manning Passing Academy.

Shortly after the workout ended, he had an invoice sent to Broncos WR Eric Decker from the Duke University football department. It made it look like Decker owed more than $3,000 for participating in the camp:

Additionally, Manning also had this letter sent to a bunch of other NFL players who worked out at the camp—including Wes Welker, Victor Cruz, and Demaryius Thomas—to make sure that the prank worked:

Good one, Peyton. As usual, excellent execution.

RELATED: The 20 Greatest Injury Comebacks in Sports History

[via Kissing Suzy Kolber]