"Lil' Crime Stoppers" is the sixth episode of Season Seven, and the 102nd overall episode of South Park. It aired on April 23, 2003.
The boys start their very own South Park detective agency. After they return a missing doll to a little girl, the police department recognizes the boys' efforts and officially names them, "junior deputies." Their next assignment - to break up a meth lab.
The boys decide to play detective and go around the town solving minor "crimes." They first investigate the disappearance of a pie left sitting on the windowsill of an elderly couple's home. After examining the scene of the crime, they come to the conclusion (based on no evidence at all) that the husband wanted the pie, but as his wife wouldn't allow him to eat it yet, he decided to brutally murder her and dispose her body in a gruesome manner. Before he could go through with the plan though, the pie had already been eaten by their dog, where the boys found it. Horrified by their outrageous accusations, the couple hurriedly send them away but not before giving them the dollar they had promised.
The detectives next case involves the recovery of Sarah Peterson's stolen doll. They corner their first suspect, Butters (for no particular reason), and demand that he remain in Cartman's bathroom to produce a semen sample. They then get a tip, which they follow, and manage to recover the doll from Bill and Fosse's house, though they had to wrestle the case away from some kids playing FBI, one of them named Agent Tucker. The recovery gets them recognized by the South Park PD, and they are made Junior Detectives. However, the police lieutenant then begins to assign them cases that should be reserved for full detectives, including busting a meth lab, which, because of the actions of the drug dealers themselves, leads to the deaths of every suspect inside.
Other detectives mock the boys, and it is revealed to them that many of the cops on the force are corrupt and that the boys can do nothing to stop it (though they don't really plan to, or even care for that matter). The boys are then sent to a strip club owned by the leader of Colorado's greatest drug cartel, who was behind the original meth lab. Before the boys enter you see the drug boss, Gino in his office talking, and he mentions that he wants the McCormicks to start making meth again.(McCormick is also the family name of Kenny) When they arrive a shoot-out ensues, though the boys have nothing more than hands which they pretend are guns (while yelling "bang bang").
Cops show up to give the boys backup, but it turns out that two of them are working with Gino, and they shoot the one good cop (He survived, as the gunshot wound wasn't fatal). They then kill Gino, so that together they get all the money; one of those cops then kills the other, and then the last person he can't trust, himself. The boys are credited with cleaning up the police force and are offered positions as full detectives. The boys, however, find reality more intense than their game, and decide to play laundromat instead, returning to Cartman's basement. When Butters arrives he declares that, having tried for the entire episode, he has managed to ejaculate and produce a semen sample. He managed this feat by thinking about Stan's Mom's breasts. However, they aren't playing detective anymore, so they no longer want a semen sample, though Cartman offers to clean his pants for him.