Self-explanatory. #1 - If you are up big for the last posession do not attempt to score. #2 - Do not celebrate prematurely, comebacks happen and you end up looking like a tool.
If you're under the basket and the offensive player is driving right into you for contact, you can only avoid getting a blocking call by jumping in the air with your arms straight up.
I normally play casually but here are some of my unspoken rules off the top of my head: 1. Do not be inconsistent with allowable level of physicality on both offense and defense ie. call a foul everytime someone breathes on you yet hack the crap out of your opponent and call him a p***y when he calls foul. 2. Playing hard is fine but losing control of your emotions in a negative manner is for biatches (fighting/getting angry etc). 3. If you have missed the last 10 shots in a row and continue demanding the ball, maybe try passing you dick. 4. if you wear one of those one armed sleeves Iverson made famous you are bad at basketball. 5. If you perform a behind the back pass when it is completely unneccesary, would have zero benefit and it results in a turnover, you are a dick. 6. If you are complaining about team mates not playing defense then get scored on while complaining, you are a dick. Probably will think of more later
When Sasquatch pulls out his blade, make sure you aren't the only white boy there. Or make fairly sure if you are that you can outrun him when the time comes if necessary.
Don't pose with Hakeem's MVP trophy immediately before playing against him in a pivotal playoff game. (i.e. the "Robinson Rule")