TYBEE ISLAND, Ga., May 1 (UPI) -- Zac Efron and Robert De Niro showed off their muscles this week on set.
The 27-year-old actor and his 71-year-old co-star stripped down for a spring break scene in Dirty Grandpa. Efron stars as an uptight groom-to-be whose perverted, former Army general grandfather (De Niro) tricks him into driving to Florida days before his wedding.