At the Post Office........

A man writing at the post office desk was approached by an older fellow with a post card in his hand...
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The old man said, "Sir, could you address this post card for me?"
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The man gladly did so, agreeing also to write a short message and sign the card for the man.
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Finally, the younger man asked, "Now, is there anything else I can do for you?"
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The old fellow thought about it for a moment and said, "Yes, at the end could you just put, 'PS Please excuse the sloppy handwriting'"