The Rock And Zac Efron Have Tire Shrugging Contest On Baywatch Set

I lift things up and put them down.

Zac Efron added even more muscles to his already athletic frame, so that he could convincingly portray a former Olympic swimmer in Baywatch ...and to look good next to his beefy co-star Dwayne "The Rock" Johnson. But what's the point in having all those muscles if you don't show them off every now and then?

"Production for the day has ended, all the extras are going home and the sun's going down. Me and Zac Efron refuse to quit in a tire shrugging contest that lasted for hours," Johnson wrote on Sunday. "Why? Because we're Baywatch, we're bad ass and we're a slightly dysfunctional family."

Who won? The Rock "kicked his candy ass."

The Rock also praised Efron on the "hard work he put in" to get in "insane shape" for the film. "That's the way you make a character iconic," he added.

"Blood, sweat and respect. The first two you give, the last one you earn." Learned that from @therock who I happened to get in a tire flipping race with on #Baywatch. Needless to say I lost this one - come at me on the 50 yard dash and we'll see what happens, Sasquatch ;)

A photo posted by Zac Efron (@zacefron) on Mar 6, 2016 at 11:24am PST

Seth Gordon (Horrible Bosses, Identity Theft) is directing the film, based on a script by Damian Shannon and Mark Swift. Baywatch is expected to land in theaters May 2017.