joker

(jōˈkər)

1. a. One who tells or plays jokes.
   b. An insolent person who seeks to make a show of cleverness.
   c. Informal An annoying or inept person: Some joker is blocking my driveway.
2. Games A playing card, usually printed with a picture of a jester, used in certain games as the highest-ranking card or as a wild card.
3. A minor clause in a document such as a legislative bill that voids or changes its original or intended purpose.
4. An unforeseen but important difficulty, fact, or circumstance.
5. A deceptive means of getting the better of someone.