South Park Episode 706 - "Lil' Crime Stoppers"

When Stan and Kyle feel that their play time no longer has any meaning, they decide to become pretend Police Detectives in order to make a difference.

When an assignment goes wrong Cartman, Kyle, Stan and Kenny learn the true meaning of being a pretend cop, and the duties behind it. When it all came down to the nitty gritty, things become too much to handle, and they pretend to be laundry mat attendants instead.