When students see the hot spark and hear the sharp bang they are suitably impressed that this charged capacitor is something to treat with respect. With our Van de Graaff this spark can often be 2 cm long, or more, and quite thick and bright. Now recharge the capacitor, as before. Set it down on the table. Turn off the VDG if you wish, so the room is quiet for dramatic effect.
Most students recoil from it and refuse.
I'll do it myself. Casually take the metal inner can in your hand and set it on the table, or other insulating surface. Some students wonder at your daring. Set the insulator down. Handle the can freely.