Grab a sheet of paper, cut a regular triangle out of it. Mark its center (you can grab a ruler and draw a line from every vertex to the middle of the opposite side; the center is where all three lines meet). The segments going from the center to the vertices divide the triangle into three equal parts, so mark them with numbers 1, 2, 3.Then take a toothpick or something like that, run it halfway through the triangle exactly at the center, and you're done! To "roll" it, just spin it like a top. It lands on one of the sides, and the number of that side is the rolled result.
Is that good enough for you? 
. This is obviously meant to trick people into saying 1/5 immediately.