"Ow!": Justin Bieber Hit with Bottle - on Tape

A video that's only now surfaced but quickly gone viral, on YouTube, shows teen sensation Justin Bieber being hit on the head by a thrown plastic bottle while onstage during a radio station concert in Sacramento, Calif. in December.

He pulls back, exclaiming, "Ow! That didn't feel good! I don't know why she just threw that at me."

Bieber wasn't' hurt, and stayed calm.

"It all went down at the Jingle Ball concert back in December," says celebrity website TMZ.com, "when some … concertgoer with an incredibly accurate arm fired off the water bottle while Bieber was front and center."

And, kids MTV.com, "His hair also remained intact."