headbutting etiquette

A week after the World Cup Final, soccer fans are still buzzing over Zinedine Zidane's crushing cranial blow to Marco Materazzi's chest. Why would a seasoned competitor like Zidane release his anger so impulsively, prompting his removal from the last game of his career? What could have provoked such a senseless act of violence? Has Materazzi even met Zidane's mother? Both footballers' parents apparently share a love for alliterative names - could they be related?

I don't have answers to any of these questions - but I do believe the world is sorely in need of a comprehensive grammar of head-butting etiquette, and I am ready to begin that conversation here. We need to decide when a violent forehead punch is appropriate conduct, when a sock to the sternum may be overstepping boundaries, and when it's just clearly out of line. I have provided a series of hypothetical situations to consider, and color-coded them to show my own opinions: in red where head-butting may be appropriate, yellow for borderline situations, and blue when you might want to just turn the other cheek. It may be too late now for Zidane, but I hope to spare others the pain and humiliation (as well as penalties) of any future head-butting faux-pas.

A vet calls your dog a bitch.
An Italian calls your mother a whore.
A senior administration official calls your wife a secret CIA operative.

A protester burns your nation's flag.
A Klansman burns a cross on your lawn.
An arsonist burns your house down.

Petty theft.
Grand theft.
Identity theft.

You're fouled but it isn't called.
Your doctor amputates the wrong toe.
You're sent to Guantanamo Bay without a trial.

I'm pretty sure there are countless other principles of headbutting etiquette to explore. Even with just these few examples, though, it's apparent that with a little thought almost any situation can be addressed productively without leveling the other guy. So I would just encourage everyone to think these things through; to pause and consider your options; to use your head, before you use your head.