PHOTO: Can You Imagine What Robert De Niro Did to Zac Efron’s Butt

Actor-Robert De Niro is playing with Zac Efron, but he is doing so in his butt!

The two were on set shooting “Dirty Grandpa” in Georgia, USA, and for De Niro, that was the time to dig his thumb into someone’s butt…LOL

So De Niro is not just great but also crazy.