Pro: It's good that plenty of people do not seem to have been in a scrap before. Long may it continue.
Con: Naivety can be a dangerous companion.
A friend of mine works in the forensics lab for the cops. The amount of stabbings they deal with is absolutely frightening. Then again, I'm sure it's directly related to the area you live in. That being said, carrying a knife around is a bad bad idea.
Obviously, you have to judge every situation individually - but I am a strong believer in picking your battles. A lesson learnt harshly in my youth.
On a side note - I don't trust poultry based fast food outlets. Sly bastards. Cow for me.