The sermon

One shabbes, Rabbi Bloom told his congregation, "Next week, my sermon will
be all about the sin of lying and to help you understand it better I would
like you all to read Leviticus chapter 28 before next week."
The following shabbes, at the start of his sermon, Rabbi Bloom asked his
congregation, "How many of you have read Leviticus 28?"
Every hand went up.
Rabbi Bloom smiled and said, "Leviticus has only 27 chapters. I will now
proceed with my sermon on the sin of lying."