Someone wasn't burped properly.

Performing "Out of Town Girl" during a concert in Arizona, the boy wonder did a milky chunder! Poor Justin turned his back on the crowd, bent over and released his milky spew, before running off stage.

It wasn't long before Biebs was back, a true professional.

"It's hard for me, you know, not feeling great and throwing up in front of a bunch of people.

"Will you love me even though I'm throwing up on stage?"

He finished the show and later took to Twitter to lol it off via an Anchorman reference.

"And .... Milk was a bad choice! Lol"