Palmer walked onto University of Phoenix Stadium wearing the inflatable white and pink mythical creature before the Cardinals' 28-17 loss to the Dallas Cowboys on Monday Night Football.
"When it is Monday Night AND the home opener, you have to arrive in style," the Cardinals tweeted with a video of Palmer walking into the stadium.
The Cardinals have a challenge between their quarterbacks at practice called the bucket challenge. The loser has to wear some type of costume, at the winner's discretion, to the stadium and warm up with it or wear it on the team flight for a road game.
When it is Monday Night AND the home opener, you have to arrive in style. pic.twitter.com/yUE14CSSbk— Arizona Cardinals (@AZCardinals) September 25, 2017
The bucket challenge consists of throwing a football inside a bucket (trash can). If you hit the bucket, you get one point. If you hit inside the bucket, you get five points.
Palmer, 39, played a bit better in the actual game, completing 29-of-48 passes for 325 yards and two scores.