I work on Halloween, but I asked my boss if we could come into work in costume, and his reaction was rather priceless. He looked at me for a minute, and went "Uhh... normally, I'd say we could see if we could work it out, but with you being the one asking, I'm not so sure. You'll probably come in with some elaborate costume with ridiculous everywhere that takes up half the store." ~laugh
But my birthday is the day before Halloween, and I have that day off, so we might try to do something fun.