Justin Bieber Plays With Mason Disick in the Pool: See Mom Kourtney Kardashian’s Cute Pic!

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A photo posted by Kourtney Kardashian (@kourtneykardash) on Mar 28, 2015 at 9:19am PDT

Babysitter Biebs? Kourtney Kardashian had no problem with her 5-year-old son Mason Disick hanging out with Justin Bieber. In fact, the proud mama, 35, shared a cute shot of her eldest child riding on the pop star's back while in the pool on Instagram on Saturday, March 28. 

Little Mason appears to be drumming on the "Boyfriend" singer's shirtless back in the snap.

The Canadian bad boy has been spending lots of time with the Kardashian-Jenner clan lately. He recently appeared with Kendall Jenner in Vogue's new "Brat Pack" spread and has been photographed several times with momager Kris Jenner out and about.  

In fact, Kris reposted Kourtney's Instagram, writing, "#Mason & @JustinBieber family pool day!!! #bestbabysitterintheworld #Repost @justinbieber ???Mason is cool as a fan."

Later that night he surprised fans by making a stop on Ariana Grande's Honeymoon Tour in Miami. The pair performed "Love Me Harder" on stage together, much to the screaming crowd's delight. 

"Thank you @ArianaGrande and thank you Miami. I missed the stage. See u soon ;)," he tweeted after the show. "Great night. Loved being back on stage. Miami I'm not done yet."

Had fun with u Ariana, even tho I forgot all the words haha

A photo posted by Justin Bieber (@justinbieber) on Mar 28, 2015 at 8:46pm PDT

He also copped to an onstage faux pas, writing on Instagram, "Had fun with u Ariana, even tho I forgot all the words haha."

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