I had my five-year-old little brother (whose experience in video games is limited to some car racing games) ask me to show him some of my games. Of course, I had to stick to the more kid-friendly titles....
So, I showcased him, in this order: Insaniquarium, Starbound, Goat Simulator (he enjoyed that one quite a bit), Tropico 4, and Star Control II: Ur-Quan Masters.
Then he kept asking for something "really scary". He assured me that he likes scary things, and isn't really afraid of anything.
Next game I showed to him was Spooky's House of Jump Scares. He isn't bothering me any more.