Never get personally involved on a case. (Season 7, Episode 21)

Rule #10

Never go anywhere without a knife. (Season 1, Episode 13)

Rule #9

Never assume. (Season 9, Episode 21)

Rule #8

Never take anything for granted. (Season 3, Episode 10)

Rule #8

Always be specific when you lie. (Season 1, Episode 23)

Rule #7

Never apologize. (Season 7, Episode 12, but referenced previous times without a number attached)

Rule #6

You don't waste good. (Season 8, Episode 22)

Rule #5

The best way to keep a secret? Keep it to yourself. Second best? Tell one other person, if you must. There is no third best. (Season 4, Episode 11)

Rule #4

Never be unreachable. (Season 3, Episode 13, Gibbs)

Rule #3

Don't believe what you're told. Double check. (Season 1, Episode 1, Mike Franks)

Rule #3

Always wear gloves at a crime scene. (Season 1, Episode 1, Mike Franks)

Rule #2

Never screw over your partner. (Season 4, Episode 14, Gibbs)

Rule #1

NCIS Quotes

McGee: All right. Well you should probably know that Abby and I used to date?
Bishop: Ew. Like, each other?
McGee: Yeah.
Bishop: Wait - isn't that a violation of rule 12, never date a....
McGee: It was a long time ago. After we'd broken up, one night I went to her lab. Found a scribbled piece paper; a list. Potential boyfriends had to fulfill certain conditions by a pre-arranged date or else, goodbye.
Bishop: Such as.
McGee: Things started off relatively normal: opening the door for her, flowers, putting the seat down. Then around number 8, it gets uh...
Bishop: What?
McGee: Does she know you have these?
Bishop: Does she know you have these?
McGee: Yeah she wasn't happy when she found out.
Bishop: These are all very specific.
McGee: Yeah.
Bishop: These ideas apply to you?
McGee: No those rules weren't in place when we were together. At least I don't think so.
Bishop: What's with the two month cutoff? Abby's sabotaging herself. I've seen stuff like this before. We have to talk to her.

I'm more of a Super-Mario guy, myself.

Captain Wescott