Zac Efron and Robert De Niro Go Shirtless, Flex Their Muscles

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Zac Efron and Robert De Niro know how to tease a movie.
They may not be shirtless in poster form yet like the Magic Mike XXL cast, but both Efron, 27, and De Niro, 71, are showing off their bodies. 
On the set of Dirty Grandpa in Georgia, Efron and De Niro were spotted in a flex-off!
Photo: FameFlynet
And wait a minute, is that an eight-pack, Efron?
Photo: FameFlynet
De Niro is also looking good and fit as he's seen here doing a push-up.
Photo: FameFlynet
These pics come after Efron was spotted in a fringe crop top and neon green pants as well as nothing but a nude-color pair of undies! 
Talk about ways to tease a movie!
In Dirty Grandpa, Efron plays an uptight guy who is about to get married and is tricked into driving his grandfather (De Niro), a perverted Army general, to Florida for spring break.
The film is set for release in August 2016.
Check out the video below for more of Zac flashing his abs for the highly anticipated comedy.