I've noticed that of my 4, Jonathan is the easiest to scare. When he comes to me at night after a bad dream (it's only happened a few times) we talk about it and in little bit he feels better and goes back to bed. There's a way of laughing that communicates a shared joke. It's hard distinction to express, but usually when I scare one of my kids (I'm a congenital practical joker. Seriously, it runs in the family.) they laugh with me, then try to scare me. And when one of them does get one on me, I laugh with them and compliment them. That shows that you can be the source of amusement without being the butt of a joke.