Rule 945 

Taken from XKCD comic number 945. xkcd.com/945/

A unnecessary or pointless use of the word "sorry". The rule states:

Rule 945 can be invoked by anyone who hears the word "sorry" in a circumstance the person saying it has no responsibly in the situation. Punishments vary from person to person, but the general rule of thumb is to ignore the person until they a) hand you the latest XKCD comic, printed on A3 paper, b) give you a hug, c) have pity sex with you, d) bring you hot chocolate and comfort food whist you cry (in situations where comfort is needed)

"My cat died" "I'm sorry" "rule 945"
"My mom's house burned down" "Oh, I'm sorry" "I call rule 945 on that"

"damn, i burned the chips again" "Sorry" "Rule 945"

Rule 945 by popelady November 13, 2011

Rule 37 

If it exists, there is a conspiracy behind it.

37 is the only two digit number in base 10 with the following property: The difference between the two digits equals the square root of the difference between the number itself and the least common multiple of the two digits.

Rule 37 works for everything: What is your body temperature?

Rule 37 by Kokonatsupaifurai February 4, 2010

Rule #3 

NEVER Shit At School! Ever.

If you feel your stomach rumbling just stay home and save yourself the embarassment and shame. NEVER, Rule #3.

Rule #3 by TapeGuy May 27, 2008

Rule 9 

There is no rule 11

Guy:..... Wait where is rule 11?
Guy 2: Rule 9

Rule 9 by Dr. Crowley January 24, 2010

Rule 34.5 

If it exists, there is a subreddit of it.

Anon: Nice picture of a penny. Don't you think that belongs to /r/numismatics?
OP: I didn't even realize that exists!
Anon: Dude, Rule 34.5

Rule 34.5 by thegame2010 March 30, 2013

Rule 152 

For any given song that exists there is a dubstep version of that song.

Similar to rule 34 in that pointing out any song that has not been dubstepped, will be made into a dubstep.

Person 1: Do you think there is a dubstep for the theme of "full House"

Person 2: Of course! Rule 152, bro.

Rule 152 by Specialmitch January 17, 2012

Rule 43A

The more beautiful and pure a thing is, the more satisfying it is to protect it.

Person 1: I'm going to create a dark fan fiction of this innocent animé character.

Person 2: I won't let you!

Person 1: Why not?

Person 2: Rule 43A, man.

Person 1: ... Fine.

Rule 43A by Arnen August 14, 2012