A man knocks on the door of his doctor’s surgery and walks in. “Hello, doctor. Please help. I just don’t know what’s wrong with me. Goodbye.” With that he turns around and walks out.
30 seconds later he is back. “Hello again, doctor. Please help. I just don’t know what’s wrong with me.”
The Doctor looks up from his desk and says: “Mmm. I think you have a serious case of double entry.”
