The Gay Spy favourite has been revealed as the Master of Mischief judge for Maynards Sour Patch Kids' Facebook competition 'Pitch Us Your Stitch Up'.
He's encouraging the nation to submit their ultimate pranks and will select a winner, who will receive £2,000 prize money and see their practical joke become a reality.
No stranger to having a few pranks played on him by the other McFly boys, Harry was up for being tied to a lamppost in his underwear for the cause.
"Being in the band, we are always playing pranks on each other so when Maynards Sour Patch Kids asked me to be their Master of Mischief, it was a no brainer," he said.
"I did get a bit of stick from the guys when they saw me taped to a lamppost in my pants! I can't wait to see the entries and will be picking a well deserving prankster as the winner."