(CNN) - Justin Bieber gives new meaning to the saying, "The show must go on."
The pop star got sick during the kickoff concert of his "Believe" tour Saturday night in Arizona.
According to E! Online, he was in the middle of one song when he suddenly turned around, threw up on stage and ran off.
A little bit later, during another song, Bieber ran off again, stopping the show for a few minutes, the report said.
Bieber eventually returned to the stage and explained to his fans that he wasn't feeling well.
He continued performing.
Later that night, Bieber tweeted a picture of himself saying he was resting up for the next show. He also joked about the cause of his illness, People reported.
"Milk was a bad choice! Lol," he wrote in a nod to the Will Ferrell comedy "Anchorman."
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