....I haven't even scared a sibling, but my siblings have scared me before.
I was like 5. My parents weren't home. It was just my sisters, my brother, and I. They were making weird noises and saying that there were aliens in the wall. I was *censored.3.0*ing scared, duude. ...Later, I found out that they were hiding in the closets, but how was I supposed to know that? Lol wow.