As a little kid of less than ten, I liked fooling with the old rusty barbed-wire fences that lined the abandoned road behind my house. At one point I decided to set a trap. I strung a piece of barbed wire loosely between two trees and propped a large fence bar against one of the trees and the wire, the idea being that a large animal–like a deer–would run into the wire. The bar would then side down and hit the animal. Some time later a friend and I were running around–and I’m not sure how it happened, but he missed the wire and I ran right into and flipped over it. No joke! Fortunately the bar no longer leaned against the tree for whatever reason, so it did not clunk me.
And that tale reminds me of a time in high school my friend and I pulled a thread from his shirt and strung it across a staircase door in high school (a door going away from the steps, thank Loki) and we tripped up a girl. She laughed it off.
I just wanted to advise against setting human-sized traps, cuz, you know, these are totally typical things to do.