Pop superstar Justin Timberlake has proved that he is a kid at heart by building a tree house in his garden.

According to ShowbizSpy, the star has built the hideout to provide himself and his friends a private place to hang out in.

A source said: “Justin's still a kid at heart...he had the tree house built so he and his buddies could escape to drink and play cards.”

And if Justin's girlfriend, Jessica Biel thinks she can hang out with her beau in the tree house, she better think twice because Justin has banned Jess from entering.

The source continued: “He even posted a sign saying 'No Girls Allowed'.”

Can we be the exception please Justin?!

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Justin has fun on set....