I’ve heard the phrase hat trick lots of times, but I just learned that I’ve been wrong about what it means. It turns out to mean three successes of the same sort (esp. in a short time). Which led me to wonder why it means that. Merriam-Webster.com Dictionary to the rescue:
the term "hat trick" as it relates to sports […] originated in British cricket. A bowler who retired three batsmen with three consecutive balls was entitled to a new hat at the expense of the club to commemorate this feat. Eventually, the phrase was applied to a single player scoring three goals in any goal sport and later to three victories or successes in sports as different as horse racing and golf. The phrase finally broadened to include a string of three important successes or achievements in any field.