Parks and Recreation Season 2 Episode 7 (10/29/09)
It's Halloween in Pawnee and Leslie is obsessed with stopping a local high school kid, Greg Pikitis, from defacing the statue of Mayor Percy. She enlists the help of her boyfriend Dave to help her keep an eye on Greg and on Andy to watch over the statue. However, Leslie comes back to the office to find he defaced that and brings in Greg for questioning. Eventually his mother comes by and yells at Dave for illegally detaining the kid and he's let go. When Leslie and Andy go to TP his house, they find his real mom there. Apparently Greg hired an actor to play his mother and they rush to the statue where they find and stop Greg.
Oh and Ann throws a Halloween party which she tries to avoid Tom getting invited too. However, it turns out she's lucky Tom and his wife Wendy show up because they turn her lame party awesome.