Zac Efron has a LOT to learn from Robert De Niro in 'Dirty Grandpa'

There's a reason why they say you should respect your elders.
In the trailer that premiered on BuzzFeed, Zac Efron's character, Jason, learns about loosening up from his gramps played by Robert De Niro, who likes to chug from a flask and party on spring break. On a road trip to sunny Florida, the two encounter all sorts of trouble including Aubrey Plaza's character, who seems to have an insatiable appetite for older men.
Julianne Hough is also in the flick, and she plays a complete and total nightmare. Think Melissa from The Hangover maybe minus the bartender.
The real fun starts when Efron quits fooling around and pulls off that pullover around the 1:25 mark. Dirty Grandpa hits theaters on Jan. 22.
Warning: Some talk about drugs and sexual relations make this trailer NSFW.