I try to do nothing I will regret and regret nothing I do. That seems pretty self-explanatory, but I will elaborate.
Sometimes I am faced with decisions that tear at my moral heartstrings. Should I glance at another test paper or not? Should I gossip about so-and-so to their roommate? Should I give some money to someone who is homeless?
My goal is to make the decision that I will regret the least, whatever it may be. I make the choice that will leave me with the least amount of guilt, if any is to be felt.
But sometimes the "right" path isn't always available to me. So that's where the second part of the code comes in to play. If I can't make the choice I won't regret, then I refuse to regret the choice that I made. Regret leads to guilt which will lead to indecision or bad decisions the next time the same scenario comes up.
So far I have managed to lead a pretty stress-free life by this honor code. If this code works for you, feel free to live by it. If its not for you, I wish you luck in finding your own way of the samurai.