Definition of "punch line" []

• The climactic phrase or statement of a joke, producing a sudden humorous effect. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "He laughed until the punch line sucker-punched him — then he froze."
• "Give a big hello and introduction, and in ten words or less catch them up: “We were just talking about this veterinary psychologist I met…” If you were just at the punch line and don’t want to stop, put your arm around the guest or take hold of her in some way while you finish so she doesn’t have that awkward I-got-here-at-the-wrong-time feeling."