- Just about all of Detective Hayes' wise-cracks.
- This line from the episode "John Deux".
John: I'm not hysterical - there's something wrong with me!Dr. Arrogant: Well, I'm certainly not going to argue that.
- Yeah John, you kinda walked straight into that one.
- Digger, just Digger.
- I liked it when he told John he should start wearing a cape and some tights.
- "There are 342,204 inactive social security numbers allocated to dead or missing persons. So, I had my pick of names."
- So naturally... he picks John Doe.
- The scene in "Mind Games" when John realizes that despite his knowledge of virtually everything else, he knows nothing about kids.
Frank: Don't you know anything about kids?John: Yeah, the average ten-year old male grows 54 point...Frank: Oh man...
- Karen's art projets may qualify, depending on your tastes.
- In "Illegal Alien," Avery asks John if he knows anything about any clandestine space program experiments, and he says he doesn't. The goofy expression of joy on John's face when he realizes he doesn't know something is priceless.
Avery: Does that mean there's isn't one? Or it's so secret that not even you know about it?John: Both...neither. I don't know. Good question, though...
- On the way to a meet a physics professor in "Past Imperfect", John and Karen are hassled by a pretentious hippie type who's ticked off about Karen's leather shoes. John shuts him down in hilarious (and awesome) fashion:
Hippie: You know many living creatures had to die so you could strut around wearing the latest fashion?
John: Zero. Her shoes are crafted from Clarino, a synthetic leather alternative perforated for breathability, designed to fit around the foot to give the same look and feel as leather.
John: No bull. That's the whole point. Your sweater, on the other hand...
Hippie: It's wool. No sheep had to die for this.
John: Judging by its hand-dyed, two strand yarns, that's actually Australian spun wool. Did you know the Australian government permits the slaughter of five million kangaroos annually? They consider them pests because they eat the grass the ranchers need for their sheep. Nice chatting with you.