Marriages may come and sex video r kellygo, but the bromance between Ben Affleck and Matt Damon is forever.

Affleck could not let National Best Friends Day pass without giving an Instagram shoutout to his number one, Matt Damon.

The actors have been serious #FriendshipGoals since they were children -- in fact, their friendship is so strong that the delightful Mindy Kaling and her friend Brenda Withers were inspired to write a play about them.

The 2002 off-Broadway hit, Matt & Ben, based on the duo's journey to write the Good Will Huntingscript, immortalized their bromance -- just like this throwback picture.

On Wednesday, Affleck celebrated their friendship by posting a photo collage of snapshots from one of Matt Damon’s past birthday parties. A youthful-looking Damon appears to have pushed his buddy Ben’s face into his cake, as best friends do.

Affleck captioned the adorable post, “This guy. #NationalBestFriendsDay.”

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Be right back -- swooning.

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