Many years ago, when I was young, reckless and hanging around in all the wrong sort of company a junkie I met gave me some street survival advice: if you're about to be mugged, act as if you're crazy in the head. It will put the muggers entirely off their game. Too much uncertainty as to how you'll respond to risk it.

Nobody's as yet tried to mug me, but I've always believed this to be an example of pure folk wisdom and have secretly hoped for an opportunity to measure its effect.

Although, come to think of it, why should I listen to advice from a junkie?