Hot At Any Age! Shirtless Zac Efron, 27, & Robert De Niro, 71, Flex Their Muscles On The Set Of 'Dirty Grandpa' -- 10 Ab-tastic Photos
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/l7yBq8ce6/480x251/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg?position=top 480w, https://media.radaronline.com/brand-img/l7yBq8ce6/640x335/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg?position=top 640w, https://media.radaronline.com/brand-img/l7yBq8ce6/768x402/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg?position=top 768w, https://media.radaronline.com/brand-img/l7yBq8ce6/1024x536/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg?position=top 1024w, https://media.radaronline.com/brand-img/l7yBq8ce6/1280x670/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg?position=top 1280w, https://media.radaronline.com/brand-img/l7yBq8ce6/1440x753/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg?position=top 1440w, https://media.radaronline.com/brand-img/l7yBq8ce6/1600x837/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg?position=top 1600w, https://media.radaronline.com/brand-img/l7yBq8ce6/2160x1130/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg?position=top 2160w)
Apr. 30 2015, Published 7:30 p.m. ET
Zac Efron, this is your future — if you're lucky! The 27-year-old compared notes and muscles with acting legend Robert De Niro, 71, on the set of Dirty Grandpa in Georgia today, and RadarOnline.com has the jaw-dropping photos.
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/dzpLp14wU/480x270/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg 480w, https://media.radaronline.com/brand-img/dzpLp14wU/640x360/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg 640w, https://media.radaronline.com/brand-img/dzpLp14wU/768x432/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg 768w, https://media.radaronline.com/brand-img/dzpLp14wU/1024x576/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg 1024w, https://media.radaronline.com/brand-img/dzpLp14wU/1280x720/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg 1280w, https://media.radaronline.com/brand-img/dzpLp14wU/1440x810/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg 1440w, https://media.radaronline.com/brand-img/dzpLp14wU/1600x900/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg 1600w, https://media.radaronline.com/brand-img/dzpLp14wU/2160x1215/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-PP.jpg 2160w)
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/HjmIILihT/401x500/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-006.jpg 401w)
While filming a new scene for his upcoming feature film, Efron took off his shirt for a flex sesh with De Niro.
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/bjmk_nFJX/388x500/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-005.jpg 388w)
De Niro is nearly 50 years older than Efron, but he gave him a run for his money!
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/8PplS3t-3/377x500/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-007.jpg 377w)
In this photo, Efron stays in perfect form as the elderly actor lifts him over his back, showing him who is really the muscle man!
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/ymyS21IuB/392x500/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-003.jpg 392w)
As RadarOnline.com reported, Efron is making a huge comeback this year and he has several movies in production.
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/I2MTEgKIU/398x500/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-002.jpg 398w)
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De Niro seemed almost upset at how ridiculously hot his younger co-star is. It is just not fair!
![//zac efron shirtless muscles robert deniro bad grandpa](https://media.radaronline.com/brand-img/Z6lzOPob2/333x500/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-010.jpg 333w)
Efron showed off his gymnastic abilities as he got some help with a handstand off of De Niro's left arm.
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/B2UPY6l-J/376x499/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-004.jpg 376w)
Dirty Grandpa tells the story of an uptight guy who is tricked into driving his grandfather, a perverted former Army general, to Florida for spring break.
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/TWPekoGsA/389x500/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-001.jpg 389w)
Efron and his De Niro are naturals!
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/ow4DxG1It/361x499/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-008.jpg 361w)
"You talkin' to me?"
![Zac Efron Shirtless Muscles Robert DeNiro Bad Grandpa Set](https://media.radaronline.com/brand-img/TC1QY6nk5/399x500/2015/04/zac-efron-shirtless-muscles-robert-deniro-bad-grandpa-009.jpg 399w)
De Niro had the brawn to do it, but he used a stunt double to throw Efron over the shoulders.