Shirtless Zac Efron and Robert DeNiro get to flex their brawn in new trailer for rowdy road trip movie Dirty Grandpa

Zac Efron plays an uptight lawyer who gets tricked into taking his grandfather - played by Robert DeNiro - on a road trip to Daytona, Florida in Dirty Grandpa.

The 28-year-old actor and the 72-year-old legend let loose in a big way as they tear off their shirts in the movie's final trailer ahead of the US theatrical release on January 22.

Zac flexes his muscles and thrills the masses in one hilarious scene during a guys' shirtless contest, and DeNiro shows off his impressive torso too.

Scroll down for video 

Mr. Olympia wannabe: Zac Efron and co-star Robert DeNiro flex their muscles in a new trailer for road trip flick Dirty Grandpa

Mr. Olympia wannabe: Zac Efron and co-star Robert DeNiro flex their muscles in a new trailer for road trip flick Dirty Grandpa

The 1.27 miniute clip begins with Jason Kelly (Zac) getting cajoled into driving his recently widowed grandparent Dick Kelly (DeNiro) to the Sunshine State.

'Your grandmother and I were there this time every year,' Dick tells his grandson.

That presents a conflict for Jason, who is just days away from getting married to Meredith (played by Julianne Hough).

You looking at me? Robert DeNiro rips open his shirt in the hilarious scene that takes place during a men's shirtless contest in Daytona Beach, Fla

You looking at me? Robert DeNiro rips open his shirt in the hilarious scene that takes place during a men's shirtless contest in Daytona Beach, Fla

Widowed: The clip begins with a funeral as DeNiro's character Dick Kelly bids farewell to his deceased wife

Widowed: The clip begins with a funeral as DeNiro's character Dick Kelly bids farewell to his deceased wife

Sunshine State: Jason Kelly (Zac) gets cajoled into driving his recently widowed grandparent (DeNiro) to Daytona Beach in Florida

Sunshine State: Jason Kelly (Zac) gets cajoled into driving his recently widowed grandparent (DeNiro) to Daytona Beach in Florida

Not so sure about this: Zac's character wears a look of concern as the road trip conflicts with his approaching wedding 

Not so sure about this: Zac's character wears a look of concern as the road trip conflicts with his approaching wedding 

His equally uptight fiancee says she's 'just freaking out' about the rehearsal dinner before telling him to take her pink MINI Cooper because she needs his SUV 'for the wine.'

On the way, Dick takes swigs from a flask and swings on the golf course in addition to flirting with a few ladies along the way.

'Grandma's funeral was yesterday!' Jason shouts and Dick replies, 'She told me to get back out there!'

Bridezilla: Julianne Hough plays Zac's equally uptight bride-to-be Meredith

Bridezilla: Julianne Hough plays Zac's equally uptight bride-to-be Meredith

Sweet-talking: Meredith (Julianne Hough) says she's 'just freaking out' about the rehearsal dinner before telling him to take her pink MINI Cooper because she needs his SUV 'for the wine'

Sweet-talking: Meredith (Julianne Hough) says she's 'just freaking out' about the rehearsal dinner before telling him to take her pink MINI Cooper because she needs his SUV 'for the wine'

Kind of girly: Zac is forced to drive his grandparent to Florida in a very small and very pink MINI Cooper 

Kind of girly: Zac is forced to drive his grandparent to Florida in a very small and very pink MINI Cooper 

Thirsty: Robert DeNiro's character is seen drinking from a flask

Thirsty: Robert DeNiro's character is seen drinking from a flask

Swinger: The 'dirty grandpa' takes a swing on the golf course with some lovely ladies

Swinger: The 'dirty grandpa' takes a swing on the golf course with some lovely ladies

Then it's welcome to Spring Break in Daytona Beach where Dick ogles the bikini-clad babes.

'You know one in three of these girls has herpes even if you can't see it,' Jason cautions his grandfather.

Zac's character gets some flack from his sharp-talking fiancee after which Dick tells him, 'If you marry her, you're going to be sleepwalking through the rest of your life.'

Spring Break here we go: Jason and Dick listen to a couple of girls talk about Spring Break in Florida and it sounds appealing

Spring Break here we go: Jason and Dick listen to a couple of girls talk about Spring Break in Florida and it sounds appealing

Sneak peek: Dick takes the opportunity to ogle one of the girls

Sneak peek: Dick takes the opportunity to ogle one of the girls

Beach babes: The guys are met with a view of scantily clad lovelies

Beach babes: The guys are met with a view of scantily clad lovelies

He's getting married: The soon-to-be-wed Jason starts to feel a little guilty 

He's getting married: The soon-to-be-wed Jason starts to feel a little guilty 

'You know one in three of these girls has herpes even if you can't see it': Jason cautions his grandfather

'You know one in three of these girls has herpes even if you can't see it': Jason cautions his grandfather

Dick then adds: 'This is our last stand.'

Jason seems to see Dick's views more clearly and that's when things get really 'dirty.'

The twosome are seen partying with the younger generation culminating in a shirtless competition at the beach among the guys.

They blend: Jason and Dick cruise down the boulevard in their very pink MINI Cooper

They blend: Jason and Dick cruise down the boulevard in their very pink MINI Cooper

Not pleased: Jason's fiancee isn't happy to hear her uptight lawyer husband-to-be is enjoying Spring Break in Daytona Beach, Fla.

Not pleased: Jason's fiancee isn't happy to hear her uptight lawyer husband-to-be is enjoying Spring Break in Daytona Beach, Fla.

'This is our last stand': Dick cautions his grandson against marrying Meredith before the two embark on a wild night of partying

'This is our last stand': Dick cautions his grandson against marrying Meredith before the two embark on a wild night of partying

Selfie session: Dick enjoys the attention of camera-wielding ladies

Selfie session: Dick enjoys the attention of camera-wielding ladies

Last dance... or is it? Zac's character enjoys a spin on the dance floor with a girl who isn't his fiancee

Last dance... or is it? Zac's character enjoys a spin on the dance floor with a girl who isn't his fiancee

DeNiro rips open his shirt to reveal rock-tough chest and abs while Efron does his best Mr. Olympia imitation.

'You know how much I appreciate you doing this for me,' Dick tells his grandson back at the hotel where they're forced to share the same small bed.

'Did you just get naked?' Jason suddenly asks in alarm.

Thirsty: Jason downs a cool beverage on the beach while his 'dirty grandpa' looks on

Thirsty: Jason downs a cool beverage on the beach while his 'dirty grandpa' looks on

This isn't the YMCA: The guys toss off their shirts and participate in a test of brawn and muscle to the thrill of the massive crowd

This isn't the YMCA: The guys toss off their shirts and participate in a test of brawn and muscle to the thrill of the massive crowd

Showing them how it's done: Robert DeNiro takes off his shirt while Zac stands there looking nervous - and that's when things start getting really rowdy on this road trip

Showing them how it's done: Robert DeNiro takes off his shirt while Zac stands there looking nervous - and that's when things start getting really rowdy on this road trip

'It's the best way to sleep,' his grandpa replies.

Zac took to social media on Thursday to share a movie poster for Dirty Grandpa, which shows the bare-chested DeNiro balancing the shirtless younger star on his shoulders,

'No joke Robert De Niro is low key as strong as The Rock. First time I saw him shirtless he did over 25 pull-ups in a row and I couldn't help but be entranced by his rippling back muscles,' Zac wrote about his co-star.

He added: 'This picture is real by the way. Like he actually did that. #DirtyGrandpa January 22!'

Thanks for being a pal: Dick thanks Jason by saying, 'You know how much I appreciate you doing this for me'

Thanks for being a pal: Dick thanks Jason by saying, 'You know how much I appreciate you doing this for me'

'I couldn't help but be entranced by his rippling back muscles': Even Zac was blown away by DeNiro's muscular physique as he shared a new poster for Dirty Grandpa on his Instagram page on Thursday

'I couldn't help but be entranced by his rippling back muscles': Even Zac was blown away by DeNiro's muscular physique as he shared a new poster for Dirty Grandpa on his Instagram page on Thursday

 

 

The comments below have not been moderated.

The views expressed in the contents above are those of our users and do not necessarily reflect the views of MailOnline.

By posting your comment you agree to our house rules.

Who is this week's top commenter? Find out now