San Diego, CA -- The voice of Charlie Brown in "A Charlie Brown Christmas" and "It's the Great Pumpkin, Charlie Brown" has pleaded guilty to threatening and stalking his ex-girlfiend and the plastic surgeon who gave her breast implants. Peter Robbins says he paid for the implants. Prosecutors say Robbins called his ex dozens of times a day and said he'd kill her and her son if she didn't give back his dog and car. They say he made similar threats and demanded a refund from the plastic surgeon. Robbins could get up to three years in prison. He'll be sentenced next month.