In ice hockey, what does the term "Hat Trick" mean?

 I don't know anything about ice hockey
 It's like the infield fly rule in baseball, only for hockey
 Throwing an octopus onto the ice
 Pushing the net out of position if the other team is about to score
 Hiding the puck under your hat and sneaking it into the net
 Stealing someone's hat while they're buying beer
 3 goals in a row
 It's like 3 card monte, except using hats
 Slamming a player into the boards so hard it makes their hat come off
 Knocking out the goal keeper.
 3 goals in one period
 3 goals by one person
 Faking the direction you're going to go with your hat, then going the opposite way

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