Ashton Kutcher ended his MTV practical joke show Punk'D in style last night by serving up a Christmas Joke to Beyonce Knowles.

In the show, the singer is mortified when her efforts to place a star on the top of a massive Christmas tree at a charity event turn disastrous.

The tree topples over, crushing presents and narrowly missing children below, as Beyonce, standing atop a huge ladder, watches on in shock. Meanwhile, far below her, kids start screaming, 'You ruined our Christmas.'

Kutcher has decided not to let the joke run too long, and he's announced that this Punk'D will be his last.