A little-known football rule, just like the drop kick. Here's the short explanation:
You call for a fair catch. Rather than run a play, you may choose to execute a free kick from the line of scrimmage established by the fair catch. And by free kick, we mean a kickoff-type kick in which the defense is not on the line of scrimmage.
The free kick after a fair catch has to be either a placekick (without a tee) or a drop kick (there's that drop kick again). Wikipedia has the details:
A team can only make a fair catch kick immediately after making a successful fair catch. If time expires while the ball is in play before a fair catch is made, the receiving team may extend the period with a fair catch kick.
When a team wants to make a fair catch kick, the ball is placed at the yard line where the fair catch was made. Both teams line up as if it were a normal kickoff, with the defense lined up 10 yards away from the ball. The ball must be put in play by placekick or dropkick, punting is not allowed as in a safety kick. Like the safety kick, the kicker cannot use a tee. But if he kicks the ball between the uprights of the goal posts, he scores a field goal.
As it turns out, I saw the last successful NFL fair catch kick on TV in a game between the Chicago Bears and Green Bay Packers in 1968. So when would you use it?:
Team A has a one-point lead and possession of the ball at their own one-yard line. There are three seconds left in the game, but it’s fourth down and Team A is going to punt, fearing that a kneel-down will leave a second left on the clock and a ‘run-around-until-the-clock-runs-out’ strategy exposes the risk of a sack in the end zone.
Now, since the clock starts on the snap on a punt, the act of kicking the ball away is likely to take up the remainder of the game time. The receiving team, Team B, would be forced to run the punt back for a touchdown in order to avoid defeat, right?
Well, maybe not. Let’s say the punt comes down at the 40-yard line. If the return man executes a fair catch, Team B could elect to use the fair catch kick option. League rules specifically state that the receiving team can still try a kick after time expires, but they cannot run a play from scrimmage. And here’s the beauty of it: Team B can choose to kick from a kickoff formation, without a defense challenging them at the line of scrimmage. In addition, the kick would be from the spot the ball was caught, not from seven or eight yards back after the snap. So, if the return man caught the ball at the 40, we’re talking about a 50-yard field goal, without any potential blockers in the way.
So now you know. Coming this summer: The Infield Fly Rule.