I've yet to come across one, but if I ever do, I wouldn't even consider stopping for them. There are simply too many terrible possibilites.
First off, I wouldn't want a stranger to be that close to me, especially when social rules dictate that we should be engaging in all manner of small talk, when I'm driving, which is a recipe for disaster if there ever was one. Conversation is hard enough when I'm stationary thank you very much, I don't need the challenge to increase further. It was a miracle I passed my damn test when the examiner started probing me on my holiday plans during the exam, damn fool shoulda quit his jibba jabba BEFORE we began.
Then there's the fact that being in a confined space with a stranger puts me at risk of catching some kind of illness. Which I'm prone to, as history has proven countless times.
Then there's the possibility that they might be some stab-happy mutilater of innocent motorists.
Or they might just smell.
Or they might be morbidly obese and damage my damn suspension.
Or I might be unwittingly assisting a jerk, by transporting them to a place where they can further facilitate their jerkitude.
Or I might run someone over by accident and the hitchhiker would be a witness, which means that I'd have to do away with them too.
Or they might be flatulent.
Or they might bear withness to my own flatulence and not hold back when showing their disapproval.
Or they might steal the pennies from the ashtray when I'm not looking.
Or they might be a Daily Mail reader.
Or the might just plain suck.
Point is, I'm not prepared to take these kind of risks. That and I'm naturally predisposed to being unhelpful, cantankerous and unaffected by other's misfortune. If they're stuck in the middle of nowhere, it was probably their own fault anyway. Damn hitchhikers cluttering up our many grassy verges, once pristine and free of unwholesome transients, but now sullied and defiled by the musty odours of roadside miscreants.
Well I'm not going to let them stand in my way any longer, I'm going to Disneyland!
Wait a minute, what were we talking about again?