One of my son's interests, which I wish he'd grow out of, is paintball. As part of his 'gear' he now has a gilly suit, a suit of camouflage snipers wear for cover, which he says makes him very difficult to see.
He's given up on trick or treating, but now excited over the prospect of a new use for his gilly suit. He asked if it was OK for him to put the suit on and lie in wait around the house on 10/31 and scare the bejeeszus out of those who come by (without the paintball gun).
Told him it would be OK, but he's not to pull this on smaller children: the last thing I need is an irate, angry parent of a scared and traumatized pre-schooler or early elementary school child to deal with.