This was posted on a board I frequent:
A new young minister was visiting the homes of his church community. At one house it seemed obvious that someone was at home, but no answer came to his repeated knocks at the door.
Therefore, he took out a business card and wrote "Revelation 3:20" on the back of it and stuck it in the door.
When the offering was processed the following Sunday, he found that his card had been returned. Added to it was this cryptic message, "Genesis 3:10."
Reaching for his Bible to check out the citation, he broke up in gales of laughter.
Revelation 3:20 begins "Behold, I stand at the door and knock."
Genesis 3:10 reads, "I heard your voice in the garden and I was afraid, for I was naked."