The episode was written by series co-founder Michael Schur and directed by Dean Holland, an editor on the series. "Greg Pikitis" featured a guest performance by stand-up comedian Louis C.K. as Dave Sanderson, Leslie's police officer boyfriend. It also featured Cody Klop as Greg Pikitis, a teenager that Leslie suspects of vandalism.
According to Nielsen Ratings, "Greg Pikitis" was seen by 4.96 million households, only a slight drop from the previous week despite direct competition from the 2009 World Series. The episode received generally positive reviews.
Leslie visits the Pawnee high school to confront Greg Pikitis, a teenager who she describes as her "arch-nemesis". Leslie warns Greg she knows he vandalizes the town's statue of Mayor Percy every Halloween, but that she will be watching him closely and will catch him this year. Greg casually denies having any such plans. At the Pawnee town hall, Ann talks excitedly about her upcoming Halloween party. She asks the others not to mention it to Tom, but she is disappointed to learn Jerry has already told him. That night, Leslie watches Greg with the help of her boyfriend, Pawnee police officer Dave Sanderson, while Andy, who now has a part-time job with the parks department, guards the statue.
Ann's party is off to a boring start and she soon starts to fear it will be a failure altogether. When Tom and his wife Wendy Haverford arrive, however, Tom spices up the party by turning the living room into a dance floor. The party is soon a big hit, and Ann thanks Tom profusely. Wendy tells Ron she knows Ron learned her marriage to Tom was a "green card marriage" to keep her from being deported to Canada, and thanks him for his discretion. She tells him they will soon be able to divorce without raising any suspicions, unaware that Tom is visibly upset about it.
After watching Greg for hours, Leslie and Dave decide to go to Ann's party. They stop at the parks department to get Leslie's costume, only to find the office has been toilet papered and vandalized. Leslie immediately suspects Greg, even though they had been watching him all night. Dave reluctantly agrees to bring Greg in for questioning, but he insists he is innocent. Andy comes in and questions Greg, pretending to be an FBI agent named Burt Macklin, but Greg is so mean to him Andy soon starts crying. Greg's mother eventually arrives and takes him away after threatening to report the trio for holding her son without proof of his guilt.
Later, Andy helps Leslie clean the parks office and, after a few beers, they decide to toilet paper Greg's house. Dave arrives in his police car and tells them he had been called to stop them. When an unfamiliar woman comes out of the house, Leslie thinks she has toilet papered the wrong house. However, the woman reveals she is Greg's actual mother, and that Greg hired a "fake mother" off of Craigslist to get him out of trouble. When she realizes Greg is not home, Leslie believes he is vandalizing the mayor statue. They go to the statue and catch Greg in the process; although Leslie wishes to have him "locked up," Dave points out he is still a minor and may only have some time in juvenile hall. Later, Leslie wonders how Greg managed to trash the parks department. The episode ends with a flashback showing Greg sneaking into the department disguised as a janitor, hiding in a dumpster until everybody leaves, then vandalizing the office.
Ann: Halloween is my favorite holiday. It's just the best. And I don't have to work! Hey slutty teenage girls dressed as sexy kittens... pump your own stomachs this year!
Leslie: William Percy. One of Pawnee's greatest mayors, and a true hero. During the Pawnee bread factory fire of 1922, he ran back into a burning building and saved the beloved secret recipe for Pawnee pumpernickel.
Dave: Didn't like 30 people die in that fire?
Leslie: He wasn't Superman.
Leslie: Hey, you're going to jail for a very long time.
Dave: He's not going to go to jail, you know. He's a minor.
Leslie: Well, we'll let the jury decide.
Dave: There's not gonna be a jury. It's a....
Leslie: Then the judge will decide where he goes.
Dave: Look, he's going to do probation. He's a minor.
Leslie: Dave, just let me have this?