I'm glad my brain doesn't play these tricks on me
My mum does have a story like this though. She was out visiting an old manor house with her Mum and Sister (classic UK thing) and they went to the toilets (classic woman thing
). Both my grandma and aunt saw a woman go to into the WC infront of them and then round the corner. One of the two stalls was closed but not locked so they presumed she went in there (they didn't mention it though).
Grandma went in the other stall and Mum was about to go in the unlocked one when her Sister told her a woman just went in there. Grandma finishes and comes out, Aunt goes in and then my Mum thinks this other woman is taking a long time so they check and nobody is in there. My grandma says that's weird because she definitely saw someone go in, my Aunt comes out and agrees with her that a woman went in there. They both said this woman was wearing the same clothes and they're both still adamant they saw this woman head into the toilets in front of them.
That's the big unexplained ghost story in my family I guess. My theory is that since that manor house has some ghost stories they have a classic trick they play on some guests and there was a secret door or something, that would be cool.