Unwritten rules you disagree with
 

What social norms that are naturally expected from you don't you agree with? For me it's people getting offended when you ask them what political party they support ... you?

A friend's ex being off limits (when they've both moved on). Sure, if the friend still has feelings for them you'd be out of order to go there, but if they've both moved on and you end up later developing feelings for each other, why not? Nobody's being hurt or betrayed in that scenario.

Interesting thread idea by the way! :)