Two skeleton gravediggers either side of a grave, grave has an infinity mirror in it. Using talking skeletons, one could say "I think you've dug the hole too deep" then the other replies "what do you think children". Use a sensor to trigger the conversation each time ToTs approach. I'm thinking...
For those interested this link is zip file of 3 joking skeleton soundtracks, each about 10 minutes long.
They are for animated talking skeletons (or other Halloween talking prop) that have a voice input, with left channel for one voice and right for the other.