There's nothing we love more than a good prank, especially when that prank involves a super cute celeb like Ansel Elgort surprising one of his super fans.

That's exactly what happened on last night's (Oct. 15) episode of 'Jimmy Kimmel Live.' Jimmy's 12-year-old niece, Alison, is a budding makeup artist with her own YouTube channel, and she just so happens to be a huge fan of the 'Divergent' star. Combining the two things his niece loves most -- makeup and Ansel -- Jimmy's definitely in the running for Uncle of the Year Award.

Let's set the scene: Jimmy invited Alison to the set under the guise of having a super famous makeup artist give her a lesson in some Halloween makeup looks. That's where Ansel comes in. Looking like an extra who just wandered off the set of 'The Lion King,' he's in full lion makeup -- fluffy mane and all.  To make things even more hilarious, the actor takes on a German persona complete with heavy accent. Talk about committing to a part.

Trying in vain to get Alison to say bad things about her favorite actor (himself), Ansel soon realizes she's totally devoted and it just isn't gonna happen. Once he finishes with her makeup, the 'Fault in our Stars' actor is met with a totally lackluster -- and totally funny -- reaction from his biggest fan. But it isn't until she begins to take off Ansel's makeup that he breaks character, saying: "You know what's so funny, when it comes off I start losing my accent." The shock on Alison's face when she realizes it was Ansel all along is seriously priceless.

Check out the hilarious prank above!

See Shailene Woodley, Taylor Swift and More Celebs' Drastic Haircuts!