Knock Three Times

What is wrong with people today? I was recently using the bathroom and locked the door. Someone from the other side, twisted the knob, jiggled it to make sure it was locked and then jiggled it again. To top it off, the person knocked loudly and then jiggled the door again. When I said "just a moment", they didn't reply. I was not taking a long time, and was at that point washing my hands. I do not understand. If the door is locked and you hear water running, someone is in the bathroom!! How annoyed am I????