i made this in class after a test... it is a little thing that will jump across a flat surface with almost no effort (if you think your cool, you can follow the pics, but if you aren't sure, just follow the steps)

Step 1: Your Paper

your paper should be small it doesn't have to be square but it helps if it is. As stated in the below comments, a notecard, cardstock, or even tickets (like for getting into events, like the "admit one" things) that is the thing i really like about these little things, you can make them anywhere, out of almost anything (as opposed to the frogs [no offense if you like the frog things])

Step 2: First and Second Folds

the next folds are simple, you should fold your paper in half (longways if it is a rectangle) then fold it back out, next fold both edges parallel to the crease in.