136465, Zac Efron and Robert De Niro show off slightly different physiques as they both go shirtless while filming a scene for ‘Dirty Grandpa’. Zac and Robert had a flexing competition before 71 year old De Niro lifted 27 year old Zac up in the air. They were up on a stage overlooking a crowd of bikini clad beach-goers as they took off their shirts and flexed. Tybee Island, Georgia – Thursday April 30, 2015. Photograph: Bruja/Thibault, © PacificCoastNews. Los Angeles Office: +1 310.822.0419 sales@pacificcoastnews.com FEE MUST BE AGREED PRIOR TO USAGE