"I grew up in a college town, 'n one Halloween our doorbell rang 'n we opened the door expecting t' see trickortreaters-- but what be in front a our open door--be another door! ...
... Like, a full-on wooden door, that had a sign that said "Please knock." So we did, 'n the door swung open t' reveal a bunch a college dudes dressed as really old grandmothers, curlers in their hair, etc, who proceeded t' coo over our "costumes" 'n tell us we be "such cute trick or treaters!" One even pinched me cheek. Then THEY gave US candy, closed their door, picked it up 'n walked t' the next house."
Replies:
Basically, knock on their door, then when they open it, they'd see a "Punch Me" note attached t' it.
If they did, I'd play the bottle a rum releasing noise, then push a plush mushroom out a flap at the top.