Johnny Knoxville, 54, Shows Off Buff Arms While Hitting the Speed Bag but Jokes He's 'Not a Boxer' The 'Jackass' alum downplayed his boxing prowess, sharing what’s really important is 'trying to ...

'Jackass' alum Johnny Knoxville downplayed his boxing prowess while showing off his arms, sharing what’s really important is 'trying to learn new things' in new social media post.

Johnny Knoxville showed off some impressive biceps — and boxing skills — while hitting the speed bag at the gym.