kicker

ot noun

1. An unexpected situation, detail or circumstance, often unpleasant. John wants to climb the wall, but the kicker is that it is thirty feet tall.
2. An unpaired card which is part of a pair, two pair, or three of a kind poker hand. Jill's hand was two pair, aces and sevens, with a king kicker.
3. An introduction; something that leads into the beginning of something. After the long lead-in, the climax of the story was a disappointment.
4. One who kicks.