Jeffrey Dahmer is a 9 year old boy with a police officer father. He was first seen in "Heavy Sledding" where he asks Frank if he's a pervert, and why he isn't at work. Frank asks him why he isn't "leaving [him] the fuck alone", to which Jeffrey threatens to tell his dad that Frank swore at him. Later he asks Sue if everyone in her family is a loser, and she throws a cigarette at his head.
In this scene, he is clearly scared of Sue when she threatens him, but exhibits an extreme amount of confidence when it comes to hurling insults at adults. Most likely due to his dad's profession.
This confidence has clearly grown in his next appearance, "Are You Ready For The Summer?. He attempts to graffiti an American flag, Frank yells at him to stop and he retaliates with "fuck you, old man!" Frank throws a beer at him, he catches it and flips off Frank for "giving [him] a free beer."
Later, he attempts to steal Frank's lawn chair and has no problem getting into a physical fight with the man.
When Dahmer's father breaks it up, we see that Jeffrey has also learned how to manipulate his father. Telling him in a frightened tone that Frank; "gave [him] a beer and then tried to touch [him]."
In "The Stinger", Jeffrey was briefly seen at the pool, making fun of Bill for having an erection. He says “And he’s playing with it” (referring to his penis). In the next scene, he teases Bill and runs away, scared, after Bridget Fitzsimmons tells him “Go shit in your fist fuckface”.
In "Bill Murphy's Night Off", Jeffrey Dahmer was shown on the video, when The Murphy Family was reminiscing about the Memorial Day parade, during the aforementioned events of "Are You Ready for the Summer?". Frank and Sue laughed about how Frank nearly killed the kid and called him a "cunt" which describes him perfectly.
- He is named after the American serial killer of the same name. His design is also very reminiscent of photos of the real Dahmer as a teenager.