South Park S07 E06 Lil' Crime Stoppers

"Four boys. One f**ked-up town."

The boys are playing "junior detectives," and have to find a kidnapped doll. After a daring rescue, they are taken back to Park County Police Headquarters. Upon their arrival, the Chief makes them "real" junior detectives and gives them their first assignment: breaking up a meth lab. The boys soon learn being real detectives isn't as fun as they thought.