I'm going to teach you something about the power of suggestion now. This is basically how hypnotism works, if you're open to suggestion a hypnotist can have a considerable influence on your behaviour. However, one doesn't have to be a professional hypnotist to see this in action.
Have you ever noticed how if someone yawns in front of you it often makes you want to yawn as well? This is a mild form of hypnotism even if it isn't intentional. Now, I've brought that example up intentionally and even thinking about yawning may be a powerful enough suggestion to make you yawn yourself.
But that isn't evil enough for me. I'm going to unleash one of the most powerful forms of suggestion. Very few people can resist this one: have you ever noticed if someone mentions headlice you have an almost uncontrollable urge to start scratching your head? When you have kids you're often on the lookout for headlice - if one kid at school gets them then all the kids end up with them.
No matter how many people tell you that headlice aren't a sign of being dirty you can't help thinking they're gross. Oh, and as soon as someone mentions headlice, most people can't help scratching their heads. How are you going with that? Trying to avoid that maddening itch on your scalp because you know there's nothing there?
Of course, the reason I bring this up is someone just mentioned headlice to me and now I can't stop scratching my fucking head. And damned if I'm suffering alone.