Michael Jackson’s kid accidentally punched him in the mouth. And his lip fell off.

Michael Jackson reportedly underwent emergency surgery after his young son accidentally punched him in the face.

The Thriller hitmaker - who has undergone multiple cosmetic surgeries on his face in the past - was recently photographed in a Los Angeles bookstore wearing numerous bandages around his mouth.

But sources tell Finditt.com the singer’s son, Prince Michael II, caused the injury: “He was whacked in the face accidentally by his younger son Prince Michael II while playing around and part of Jackson’s upper lip collapsed.

“That mishap led a hysterical Jacko to make a beeline for the plastic surgeon for a bit of quickie repair work.”

Let that be a lesson to you: If you’re going to have enough surgery to become a modern-day Frankenstein’s monster, don’t play with kids.

Some might call this karma.

Exit question: How the hell does your lip “collapse”? What, he’s got balloons for lips now?

If any of my readers are plastic surgeons, please don’t tell me the truth. I don’t want to know.