South Park: Season 6, Episode 11 - ProjectFreeTV

6 - 11: Child Abduction is Not Funny

Tweek's parents become concerned about child abduction, and though they try to teach him how to be safe, they're afraid they have failed. Other parents become concerned as well, and soon the whole town is taking drastic measures to prevent child abduction, even going so far as to erect a wall around the town of South Park.