A giant yo-yo usually about 5 inches across that can leave the string. Some beleave it is what happened when a drunk yo-yo and a horny pair of devil sticks got together. Many people who have never done it before think it's simple or will tell you to do things that are imposible.
I diaboloed for little kids once and accedentally killed him.
Hey, toss the diabolo up and to 2 back flips and catch it with your teeth.