What are some unspoken rules that all friends should abide by?

always respect the other person

There's a point where things have to stop being free. If you're constantly asking for favours, then at some point, start doing the other person favours, contributing gas money, or giving them something they'll accept as payment.

Not to stop the communication inspite of all the BS happening amidst them. Buddies remain buddies!

Hold your friends hair back if she gets sick

The only good robot is a dead robot.

Their gf is off territory