Johnny Knoxville Expecting Baby No. 3!

Credit: Kevin Winter/Getty Images

Another MTV star is having a baby -- and no, it's not one of the girls from 16 and Pregnant.

On Friday, Jackass daredevil Johnny Knoxville announced that he and wife Naomi Nelson are "having another little bambino in the fall."

"My 15-year-old daughter Madison is very excited about it," Knoxville, 40, wrote on his official Facebook page. "And her 16-month-old little brother Rocko has, well, no clue. Wahoo!"

Knoxville wed Nelson on September 24, 2010; he popped the question with a 2.5 carat Edwardian engagement ring from L.A.'s Platt Boutique Jewelry.