There was a book I wanted and couldn't find in the shops, so I ordered it on Amazon on Monday. Today, I was in Nottingham, saw it on the bookshelf and thought "Ooh, there's that book I wanted! Excellent!"
So I bought it, and halfway home suddenly thought to myself "D'oh!" And sure enough, there's a little card through my letterbox waiting for me when I get back, saying we've tried to deliver a parcel but you weren't in.