ET's Kevin Frazier and special correspondent Michelle Williams got stars from both the New England Patriots and the Seattle Seahawks to sing some of Katy's biggest hits, and even got Seahawks running back Marshawn Lynch to bust out a tune.
Instead of Katy Perry, Lynch belted out the chorus from "Nights Like This" featured on the soundtrack of the 1991 classic The Five Heartbeats.
As a reward for playing along, ET gave the players Xbox Ones -- a prize Lynch is sending to a good cause.
"One lucky kid from my [Fam 1st Family Foundation] will be going home with an Xbox One as soon as I get home from the Super Bowl," Lynch said.
While the players love to have a good time, they also love giving back, and we prepared personal messages to the players from some special fans via the Microsoft Surface tablet.
Six-year-old Maddie Herman is battling cancer and she sent a video to Seahawks quarterback Russell Wilson and Seahawks kicker Steven Hauschka.
"Maddie, it's always a pleasure. You're such a sweetheart," Russell said. "Thank you for everything you do and thank you for rooting for us. I'm praying for you to go strong against cancer. I know you'll come through and I'm rooting for you, girl."
Seahawks cornerback Richard Sherman got a message from Yvette, the sister of his best friend who died after getting caught in the crossfire of a gang shootout on the streets of Compton.
"We'll be cheering you on from San Diego," Yvette said. "Go Seahawks!"
Super Bowl XLIX, which pits the New England Patriots against the Seattle Seahawks, airs Sunday, Feb. 1 at 6:30 p.m. ET/ 3:30 p.m. PT on NBC.