What About Tuesday by Adam Wilson

Should you ever wake up to find a day of the week missing due to a freak abnormality in the nature of space-time, it's probably a good idea not to mention it to anyone. It's definitely a good idea not to mention it to the slight ginger working for Gently's Private Investigators. You may think it's a good idea, but it'll be way more trouble than it's worth.

Really, it's probably best to just go about your day and forget anything ever happened. Cause technically, nothing did.