Gibbs' Rules

Gibbs' Rules are from the television show NCIS. Leroy Jethro Gibbs is the leader of a Naval Criminal Investigation Service team composed of three agents, as well as, a medical examiner and a forensics Technician. Together, this group investigates any crime that has a shred of evidence connected to Navy and Marine Corps personnel. Gibbs has quoted rules to agents since the first episode, as the situation called for it.
　
In "Switch" (ep304) we find out that there are actually 50 Rules. They are not written down ... it is Gibbs' job to teach them to his agents. In "Deception" (ep315) the writers seem to have forgotten that they already used #3. Or did they forget? There are theories out there, among others, that because the rules are not written down the numbers may be fluid. Regardless, we now have two Rule #3s and two Rule #1s.
　
These are the rules that have been quoted thus far.

Rule #1: Never let suspects stay together.
Ep 101 "Yankee White"

Rule #1: Never screw over your partner.
Ep 414 "Blowback"

Rule #2: Always wear gloves at a crime scene.
Ep 101 "Yankee White"

Rule #3: Don't believe what you're told. Double check.
Ep 101 "Yankee White"

Rule #3: Never be unreachable.
Ep 313 "Deception"

Rule #4: 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.
Ep 414 "Blowback"

Rule #7: Always be specific when you lie.
Ep 123 "Reveille"

Rule #8: Never take anything for granted.
Ep 310 "Probie"

Rule #9: Never go anywhere without a knife.
Ep 113 "One Shot, One Kill" and Ep 120 "Missing"

Rule #12: Never date a coworker.
Ep 115 "Enigma"

Rule #15: Always work as a team.
Ep 505 "Leap of Faith"

Rule #18: It's better to seek forgiveness than ask permission.
Ep 304 "Silver War"

Rule #22: Never, ever bother Gibbs in interrogation.
Ep 410 "Smoked"

Rule #23: Never mess with a Marine's coffee if you want to live.
Ep 209 "Forced Entry"
　
Another one of Gibbs's rules which is used more often than the others, but without a number, is "Never say you're sorry, it's a sign of weakness." According to DiNozzo, another rule is "Never marry a woman who eats more than you."