https://www.youtube.com/watch?v=lfhynQHThaA

Most grandpas want toffee or socks, but Robert De Niro's "Dirty Grandpa" just wants an uninhibited romp with a college student.

With no shortage of shenanigans abound, De Niro as Dick Kelly fools his uptight grandson Jason, played by Zac Efron, into taking a hedonistic spring break trip to Daytona Beach, Fla.

The raunchy comedy pairs the veteran actor and heartthrob as two people at a crossroads in life. Jason will soon walk down the aisle with an equally uptight fiance in Julianne Hough's character, and grandpa Dick will enter a retirement home.

"If you marry her, you’ll be sleepwalking through the rest of your life. The way I see it, this is our last stand," De Niro says in the "Dirty Grandpa" trailer released Wednesday.

Efron's straight-laced Jason eventually buckles, indulging in his grandfather's every whim. He faces off against his impressively fit De Niro in a muscle flexing competition, gets into trouble with police, and partakes in drugs and booze. "I just smoked crack!" Jason proudly roars at a party.

"Dirty Grandpa" opens Jan. 22, 2016.