I forgot where I heard this joke but this seems to always be my back-up joke.
A man was looking out his window when he saw his blonde neighbor go to her mail box, look inside and close it without any mail in her hands.
He figured she was waiting for something important.
A few minutes later, he saw his blonde neighbor go back out to her mail box again, look inside and close it once again with out any mail in her hands.
When this happened a few more times, the man walked out to the blonde, whom was once again at her mail box.
He asked, “Is everything OK? Why do you keep checking your mail box?”
Exasperated, the blonde replied, “Because my computer says I’ve got mail!”