You know sometimes being paranoid works out for you:

I was round a friends house last week, and he was looking round for his 5 bucks.. He momentarily looked at me in a way that made me think "Does he think I took it?"
Why would he think I took it? Did I take it? I knew I hadn't but now I had to check..

Well I can't just check my pockets because he will think I've nicked it. I can't turn away because then he'll know I'm checking my pockets, and he'll think I've nicked it.

So I went into the toilet to check my pockets. I found his 5 bucks by the sink.

Now I can't pick it up and say I found it there cos he'll think I nicked it and I'm giving it back. I can't leave it there because he saw me go in, and he'll know I nicked it and left it there!

So I took it