The unsuspecting kid starts to reach into the bowl and a disembodies hand pokes out from the bowl and hands them a candy bar. Screams, mirth and merriment ensues.
Fake hand holding one side of the bowl, real hand on the other, the other real hand in a hole at the bottom hiding then handing out the candy.
For grownup house guests that are friends with a good sense of humor, you could also grab their hand as they reached into the bowl.
A non-Halloween variation of this could be a party trick where you play a game of "What's inside the box". Instead of a bowl of candy you have a box with a curtain on it. The person reaches in to see what was put in using only touch and the perpetrator grabs their hand.-- doctorremulac3, Nov 02 2018 I'm pretty sure this is a lawsuit waiting to happen. The cardiac arrest years happen early nowadays.-- MaxwellBuchanan, Nov 02 2018 !!!!!!
(takes fingers out of ears)-- not_morrison_rm, Nov 02 2018 random, halfbakery