The 28-year-old hottie asks his Dirty Grandpa co-star to wish his girlfriend Sami Miro a happy birthday.
Robert obliges, but his mundane “happy birthday” doesn’t really suffice for Zac. He asks him to try again with more energy and maybe some balloons.
It doesn’t go so well. Watch Bob tell them off in the video below!
“Oh my God, you better love that,” Zac tells Sami.
Zac Efron & Robert De Niro – Funny or Die Video