Nice to see how you approach a tickle-situation. There are many things to ADD to the electric toothbrush from this point. Oil up those soles and use a pair of paddle hairbrushes with little balls on the bristles and an air cushion beneath them (keeps the pressure from becoming painful). (For example, https://www.conair.com/c/1h12b130/professional-paddle-brush/975) We in the trade call these "WIdowmakers." :-) Attack the pits, ribs, hips with wiggling fingers. To be really nasty, take a couple of very soft brushes or feathers and play them around the ears and nose! (That is best if you have secured the head still!) Tickle the balls with a feather/soft brush. You can use that as a start toward bringing him to orgasm. (You can move on to your hand or magic wand.) Because, as you will tell the victim, when a boy cums he gets 10 times as ticklish, so he should keep that in mind!