I wonder what this calculation would yield:

% of rapes involving handcuffs * % of rapes standard handcuffs used in such a way that both the keyhole and key are accessible to the hands * % of rapes where the victim is left unattended and fully clothed (presumably the key is in the clothes or keys) long enough to unlock the handcuffs * % chance of victim remembering to clip the handcuff key to their clothing * % chance escaping from handcuffs will result in a better outcome for the victim * % chance victim is not under constant intimidation and control of the perpetrator

Given that the first number - rapes that involve handcuffs - seems almost undetectable and the chances of a successful beneficial escape are quite low, I'm going to say handcuff keys are the equivalent of a tin foil hat as a rape prevention tool.

Is that a really a frequent enough occurrence to justify always carrying a handcuff key? I'd say that's likely to happen to your average skateboarder about once every thousand lives. You might be better off learning self defense tactics and avoiding being handcuffed in the first place. If you were manhandled enough to be handcuffed, you're unlikely to get very far with a key.

Zombie nazi invasion!