What's so funny? Ben Affleck and Matt Damon are in hysterics as they share inside joke at Live By Night premiere

He partied with his brother Casey Affleck, who won a Golden Globe Award the night before.

But on Monday Ben Affleck celebrated his own achievement as he attended the world premiere of his upcoming Prohibition-era thriller Live By Night held at the TCL Chinese Theater in Hollywood.

The 44-year-old star was joined by his best pal and Good Will Hunting co-star Matt Damon as the pair were in stitches throughout the star-studded event.

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What's so funny? Ben Affleck and Matt Damon were in hysterics at the premiere of Live By Night held at the TCL Chinese Theatre in Hollywood on Monday night

The two-time Academy Award-winning actor looked handsome as always in a royal blue suit.

He paired the dapper look with a baby blue dress shirt, navy printed neck tie and polished black leather brogues.

Ben was quite the silver fox as he sported a neatly-trimmed beard and wide grin while catching up with his fellow Oscar-winning friend.

Hysterics in Hollywood: The Good Will Hunting co-stars couldn't stop laughing as Ben promoted his upcoming Prohibition-era thriller

Ben the babe! The two-time Academy Award-winning actor looked handsome as always in a royal blue suit

Hollywood hunk! The father-of-three was quite the silver fox as he sported a neatly-trimmed beard and wide grin 

Matt, 46, was dressed in an all black with suit and matching shirt. He coordinated looks with his stunning wife Luciana Barroso, 40. 

Damon and Luciana became engaged in September 2005 and married in a private civil ceremony in December 2005.

They share three daughters - Isabella, 10, Gia, eight, and Stella, six - and a daughter from Luciana's previous marriage, Alexia, 18.

Wisecrack: The 44-year-old Batman star appeared to whisper an inside joke to Matt, 46

Oscar winners: The best friends share an Academy Award for Best Writing, Screenplay Written Directly for the Screen for their 1998 blockbuster Good Will Hunting

Good company! Ben joined his co-stars for a group red carpet snapshot alongside (L-R) Chris Messina, Elle Fanning, Miguel, Sienna Miller, Zoe Saldana and Chris Cooper

Ben and Matt posed up a storm at the premiere for the Batman star's new film, which he co-wrote, directed, and starred in.

The Gone Girl star plays Joe Coughlin in the film, the prodigal son of a Boston police captain who becomes a bootlegger and a rum-runner eventual gangster.

He stars in the film alongside Sienna Miller, Zoe Saldana, Elle Fanning, Scott Eastwood, Brendan Gleeson and Anthony Michael Hall.

Fantastic friends: Ben and Matt posed up a storm at the premiere for the Batman star's new film, which he co-wrote, directed, and starred in

Coordinating couple! Matt was dressed in an all black as he matched looks with his stunning wife Luciana Barroso, 40

Meanwhile Ben joined his younger brother Casey Affleck the night before in celebrating his win for Best Actor in a Drama gong for his role in Manchester By The Sea.  

The 41-year-old remained calm and collected despite bagging one of the biggest awards of the night, while his dapper older sibling appeared keen to make him the centre of attention at the star-studded Amazon Golden Globes after-party.

Ben was not joined by his estranged wife of 10 years, Jennifer Garner, 44, as the couple announced their split in June 2015.

Despite announcing their intention to divorce over a year ago, the pair have not yet officially ended their marriage and continue to co-parent their three children - Violet, 11, Seraphina, seven, and Samuel, four. 

Proud: Meanwhile Ben joined his younger brother Casey Affleck the night before at a Golden Globes after-party as he celebrated his win for Best Actor in a Drama gong for his role in Manchester By The Sea

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