Halloween is an earth thing. Other worlds have their own superstitions and traditions, their own days when the dead are supposed to be able to contact the living, or the other way around, but nowhere else has turned it into such a commercialised entertainment. It’s unbelievably tacky.
Surrounded by a swarm of small trick-or-treating vampires, witches, fairies, ghosts, and superheroes, the Doctor somehow gets swept up to a front door. The owner of the house looks at him, puzzled.
“What are you supposed to be?”
“I’m the Doctor!”
“Oh. Very good, have some candy.”
Oh yes, Halloween is completely brilliant!