Of course, knowing the Kardashians, they have something special planned for him and he'll be showered with love off of social media as well, so we're sure he's gonna have a good day either way!
We just can't believe he's five already. It feels like just yesterday that Kourtney found out she and Scott Disick would be welcoming their first child together. Now, that "baby" is already FIVE and their third child is due any second now.
...and now we feel old!
Happy Birthday, Mase!
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Gallery | Best of Kourtney Kardashian Memes