By Lara Walsh
Updated Jun 09, 2016 @ 9:00 am
Matt Damon Ben Affleck BFF Day - Lead 2016
Credit: Angela Weiss/Getty

It's a bromance for the ages: Ben Affleck took to Instagram on National Best Friends Day to celebrate a very special man in his life—namely, one Matt Damon.

On Wednesday, Affleck shared a collage that shows the baby-faced Good Will Hunting co-stars sharing a special moment at what appears to be Damon's birthday party. The hilarious series of four photos shows Damon dunking Affleck's face into the birthday cake after his friend dared to put a finger in the icing. "This guy," the 43-year-old actor captioned the black-and-white throwback collage.

Affleck's post is fitting, considering the longtime friends were recently honored with a "Guys of the Decade" award at the Spike Guys Choice Awards on Saturday. The actors chose to highlight their epic friendship by making fun of other bromances that didn't quite make the cut, calling out powerful duos like George Clooney and Brad Pitt, and James Franco and Jonah Hill in their acceptance speech.

Damon ended their speech on a more serious note with a sweet shout-out to his best friend, "After decades and decades of friendship, I want to thank my ultimate man of the decade." Aw! These two win the National Best Friends Day game, hands-down.