But stunt performer and comedian Steve-O took a new kind of risk when he let actor Mark Wahlberg shave his head ... of the performer's head of a crash test dummy. He also unearthed several scars ...

Now, the 50-year-old comedian is showing off his latest change in appearance: A wild haircut given by none other than Mark Wahlberg himself ... "I had to test it a couple of times," he admitted.