you can get chock from single coil, no need for transformer... just get the bigger coil with nice core, attach wires and leave bare ends, get each with one hand and touch 6V battery for example. if you didn't feel anything, that's ok, wait till you let go...
i was testing it on couple friends and then on my teacher some 20 years ago. the big coil we had in the lab had lot's of turns of thick enameled wire but had just air core so i filled it up with couple bolts to enhance joy... then she called principal and he called my mom, but it was so worth it...
so many people don't suspect anything when they see it's not a transformer