Paper confetti is placed atop a Van de Graaff generator and flies off when the grounding rod is removed.  When turned on, a Van de Graaff generator builds up lots of negative charge on its large metal sphere. A grounding rod is used to protect the demonstrator and control the amount of charge. When the paper confetti is place on the sphere the charge jumps onto it, but since paper is an insulator, the charge cannot move and sticks to the inner side of the paper. Since there is more negative charge also on the sphere, the negatively-charged paper will be repelled away. The Van de Graaff generator was developed by Robert J. Van de Graaff, an MIT professor.