4) When a bro designates you as his wingman, you may not fail him. This is the most important role a bro may play for a bro, and may not be violated or debauched.
Rule 4 may seem like a repetition of Rule 3. But a necessary repetition it is. As stated in the post about rule 3, the wing man is the highest honor and sign of trust that can be bestowed from one bro to another. No other higher honor exists.
To fail a bro as a wing man is terrible failure. I have seen it done. The costs are great, because when a wing man is designated it is because a wing man is needed. The feeling of a guilt a bro would feel for failing a bro pales in comparison to the guilt from failing as wing man.
To fail at rule 4 is to fail at rule 1, rule 3, and probably fail at life. Honor the bro code and the sacred trust of the wing man. Keep the rules and you shall prosper as bros.