look up any word, like pussy:
 
1.
The unspoken rule that what is said between siblings about parents or other siblings, stays between siblings. It's like the man code or the bro code, but with siblings. It's like Vegas. People who violate this unspoken rule are considered untrustworthy. Breaking the code is akin to betrayal. The phrase is never said out loud unless it is being explained to someone who for some reason did not become aware of it through osmosis or other siblings' example.
Sibling1: "Dude, you can't tell Mom I said this, but she's a little oversensitive."

Sibling2: "Mom said it wasn't nice that you called her oversensitive. Then she cried."

Sibling1: "Are you freaking kidding me??!!! Look, I thought you would have gotten the hint by now, but there's this thing called the Sibling Code..."
by YourSister July 25, 2013
3 2