Ben Affleck celebrates National Best Friends Day with adorable pics of Matt Damon

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Affleck, Damon are Spike's 'Guys of the Decade'

Ben Affleck celebrated his beloved bromance with Matt Damon on National Best Friends Day with some pretty epic flashback pics.

On Wednesday, the 43-year-old actor posted a photo collage from one of Damon's birthday celebrations that showed Affleck wearing a cake on his face. "This guy," Affleck captioned the sweet Instagram post.

This guy. #NationalBestFriendsDay

A post shared by Ben Affleck (@benaffleck) on

The Batman v Superman star's tribute to his pal comes just a few days after the Good Will Hunting stars accepted the Guys of the Decade award at the 10th Spike TV Guy's Choice Awards in Culver City, California on Sunday night. "I think it goes without saying that this is an award Matt and I have been dreaming about since we were little boys," Affleck joked. "I did Gigli and Matt did that Liberace movie, and all of a sudden, it all seemed out of reach. Then I did [Batman v Superman] and all of a sudden, it was back in reach again."

Matt Damon and Ben Affleck's friendship through the years:

13 PHOTOS
Ben Affleck and Matt Damon through the years
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Ben Affleck celebrates National Best Friends Day with adorable pics of Matt Damon
LOS ANGELES, CA - MARCH 23: Oscar winners Matt Damon (L) and Ben Affleck hold the awards they won for best original screenplay for the film 'Good Will Hunting' which the two wrote during the 70th Annual Academy Awards 23 March in Los Angeles. (Photo credit should read HAL GARB/AFP/Getty Images)
LOS ANGELES - JULY 25: Actors Ben Affleck and Matt Damon talk at the afterparty for the premiere of Universal Picture's 'The Bourne Ultimatum' at the Hollywood Palladium on July 25, 2007 in Los Angeles, California. (Photo by Kevin Winter/Getty Images)
LOS ANGELES, CA - NOVEMBER 07: Actors Matt Damon (L) and Ben Affleck attend HBO Reveals Winner of 'Project Greenlight' Season 4 at BOULEVARD3 on November 7, 2014 in Los Angeles, California. (Photo by Frederick M. Brown/Getty Images)
BEVERLY HILLS, CA - MARCH 27: Honoree actor Matt Damon and actor Ben Affleck speak onstage during American Cinematheque 24th Annual Award Presentation To Matt Damon at The Beverly Hilton hotel on March 27, 2010 in Beverly Hills, California. (Photo by Kevork Djansezian/Getty Images)
JIMMY KIMMEL LIVE: AFTER THE OSCARS - The 11th annual 'Jimmy Kimmel Live: After The Oscars' special airs live on Oscar Sunday, February 28, after the late local news EST/CST and at 10pm PST on ABC. (Photo by Randy Holmes/ABC via Getty Images) MATT DAMON, BEN AFFLECK
JIMMY KIMMEL LIVE: AFTER THE OSCARS - The 11th annual 'Jimmy Kimmel Live: After The Oscars' special airs live on Oscar Sunday, February 28, after the late local news EST/CST and at 10pm PST on ABC. (Photo by Randy Holmes/ABC via Getty Images) MATT DAMON, BEN AFFLECK
CULVER CITY, CA - JUNE 04: Honorees Matt Damon (L) and Ben Affleck accept the Guys Of The Decade award onstage during Spike TV's 10th Annual Guys Choice Awards at Sony Pictures Studios on June 4, 2016 in Culver City, California. (Photo by Kevin Winter/Getty Images)
CULVER CITY, CA - JUNE 04: (L-R) Actors Robert De Niro, Matt Damon and Ben Affleck attend Spike TV's 10th Annual Guys Choice Awards at Sony Pictures Studios on June 4, 2016 in Culver City, California. (Photo by Mark Davis/Getty Images for Spike TV)
CULVER CITY, CA - JUNE 04: Honorees Ben Affleck (L) and Matt Damon accept the Guys of the Decade Award onstage during Spike TV's 10th Annual Guys Choice Awards at Sony Pictures Studios on June 4, 2016 in Culver City, California. (Photo by Mark Davis/Getty Images for Spike TV)
CULVER CITY, CA - JUNE 04: Actors Ben Affleck (L) and Matt Damon attend Spike TV's 10th Annual Guys Choice Awards at Sony Pictures Studios on June 4, 2016 in Culver City, California. (Photo by Frazer Harrison/Getty Images for Spike TV)
CULVER CITY, CA - JUNE 04: Actors Matt Damon (L) and Ben Affleck attend Spike TV's 10th Annual Guys Choice Awards at Sony Pictures Studios on June 4, 2016 in Culver City, California. (Photo by Frazer Harrison/Getty Images for Spike TV)
This guy. #NationalBestFriendsDay
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WATCH: Matt Damon Admits 'It Was Painful' Being Ben Affleck's Friend During Jennifer Lopez Romance

"Now we're the...coveted Dudes of the Decade...the Guys of the D**kheads?" the father-of-three further quipped.

"No, the D**kheads of the Decade Award. What is it called?" Damon, 45, added before getting it right. "It's the Guys of the Decade."

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The actors concluded their time on the stage with a heartfelt thank you to the troops, who they also made time for during the event. An eyewitness tells ET that the actors were surrounded by service men and women throughout the night. Damon and Affleck sat by the troops during the show and were seen taking pictures and selfies during a commercial break.

Affleck is such a good friend that he snuck Damon onto the Jimmy Kimmel Live! set after the Oscars in February. Check out the hilarious moment:

WATCH: Matt Damon Pops Out of Ben Affleck's Coat, Crashes Jimmy Kimmel's Post-Oscars Special

Matt Damon Crashes Jimmy Kimmel's Post-Oscars Special

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