Jimmy Kimmel Hilariously Wishes 'Frenemy' Matt Damon a Happy Birthday

Getty Images

Happy Birthday, Matt Damon!

The Jason Bourne star turned 46 on Saturday, and in celebration of his special day, his longtime "frenemy," Jimmy Kimmel, took to social media to send him well wishes -- well, kind of.

WATCH: Matt Damon Crashes the Emmys to Roast 'Big Loser' Jimmy Kimmel

In the hilarious post, which was shared on Instagram and Twitter, the 48-year-old host sports a gray T-shirt emblazoned with the actor's face and words poking fun at Damon's middle name, Paige.

"On this day in 1970, a monster was born," Kimmel captioned it. "#MattDamon."

MORE: How Matt Damon Bulked Up for His Highly Anticipated Return as 'Jason Bourne'

Fans of the two were quick to comment on the funny gesture, writing things like, "Friendship goals forever," "Is that a famed frame of you and Matt in the background?" and "I hope this 'feud' never ends."

The famous fake feud has been one of the most long-running gags in late night television, dating back to the early 2000s. It all started with an improvised joke during the third season of Kimmel's show, Jimmy Kimmel Live!, in which he apologized for not having enough time to interview Damon -- calling out the show's lack of A-list guests. Because the joke was so well-received by the audience and one of the producers, Kimmel made a habit of using Damon's name at the end of each episode.

"The legs on this bit are unbelievable to me," Kimmel told NPR in 2013. "I mean, people laugh every time I say it. … Repeating the same joke every single night, you'd think eventually people would get tired of it, but they don't."

WATCH: Jimmy Kimmel Surprises Idina Menzel With Matt Damon Backstage

While Kimmel has already made it clear he hasn't forgotten his pals birthday, one person we're still waiting to see a celebratory post from is Pink -- her 5-year-old daughter, Willow, has a huge crush on the Massachusetts native!

While chatting with ET in May, the pop star revealed she's actually gotten "in trouble" for telling people about Willow's infatuation with Damon.

WATCH: Pink Is 'In Trouble' With Daughter Willow for Revealing Matt Damon Crush

"She's already upset with me because there's a new game we play called Ask Siri -- which, she just found out last week there's a Siri -- and I said, 'Siri, Willow-Matt Damon' and all this stuff came up," Pink explained. "[Willow]'s like, 'How do they know?' She got mad at me!"

Hear more on Willow's adorable obsession in the video below.