Here's the first one that pops into my mind. We had a spot in our side yard, under our tree swing, where we were allowed to dig holes. We would dig huge holes (for a child), big enough to hide in. One of my favorite things to do was to tie a rope to the telephone pole across the street, which lead into the hole. We would put sticks on our rope, in the middle of the road. One of us would hide in our hole (with dirt covered cardboard covering the top of the hole). The other one would stand watch. When a car would come, the one on the outside would give a signal, and the one in the hole would give the rope a tug, causing sticks to fly up in front of the cars.
We did this type of thing so much, that the locals were getting used to us. One time, we were standing on either side of the road, pretending to be holding a rope. A delivery man came by and told us to get our rope out of the way. We told him that there was nothing there, and to go on through. He got mad and insisted that we move the rope (that wasn't there). We insisted that there wasn't anything in the way, and to go on through. (All the time pretending to holding a rope taunt). He did not believe us, turned around, in the middle of the road, and went the other way.