(Apologies for the poor art skills)

On Halloween I saw a lady wearing this, shirt/dress/top thing, and I’ve been trying to figure out what it’s called and where I can get one lol.

From the front it looked like a standard nice white button up shirt, but from the back it went all the way down to the knees or a little after I think. I can’t remember if it flared out or swept in, I think it might have swept in to a bit more of a very soft point?

If anyone has absolutely any ideas I’d love to hear them, it’s been driving me up the wall trying to find it ????.