Jusin Bieber Gets Willow Smith Again [VIDEO]

JUSTIN BIEBER

pulled a prank on WILLOW SMITH at their concert in the U.K. last weekend.  And she's vowed to dole out some payback.  Here's what went down:

--In the middle of Willow's performance of "Whip My Hair", Justin, his manager, his "swagger coach," and Willow's brother JADEN SMITH crashed the stage.

--Justin was banging on a cowbell . . . while Jaden and the rest of Justin's, well, entourage were wearing silly hair extensions and dancing around.  It was SOOOO WILD!!!

(--I love the crowd reaction to Willow.  Everyone seems a little bored until she whips her hair, and then people are like 'Yeah!'  Then, when Justin's entourage of middle-aged men comes out and starts dancing, everyone's just confused . . .)

(--And then Justin and Jaden come out and everyone goes ballistic, and hundreds, maybe thousands of girls are suddenly having the time of their lives.)

(--I could easily make the argument that Justin's "prank" is the only reason anyone cared about Willow's performance in the first place . . . but whatever.) - JB