Just because I like watching aldo squirm, I'll actually attempt to explain this.
For anyone who has never seen a game of baseball (and I metaphorically spit on those of you this applies to
), the objective of the team on offense is to advance the runners around the bases (which are arranged in a diamond shape) by hitting the ball, which is thrown by the pitcher from the center of the diamond over home plate. (I won't get into balls and strikes, since it's not really relevant to the question.) To score a run for his team, a runner must advance through all four bases, from first to second to third to home. Runners can only advance a base (or more) in certain circumstances: when the ball is hit into play by the batter, by stealing the next base, or a few other methods that I won't get into. If the bases behind a runner are full, a fielder can get the runner out (three outs ends an inning) by simply stepping on the base the runner is running to; if not, he must tag the runner with the ball. An out also occurs when a fly ball is caught by a fielder.
Anyways, in most normal cases, the batter tries to swing and hit the ball with full force, with the intent of getting a single, double, triple, or home run (hitting the ball out of the park, which means at least one automatic run, more if people are already on base). However, there are circumstances where a hitter finds it more important to advance the runners on base than to get on base himself. This usually happens when a team is down by a few runs or else wants to put up an insurance run or two between themselves and the opponent. It often involves advancing a runner from first to second base, since this makes it possible for a reasonably fast runner to score on a single-base hit. There are usually two reasonable ways of doing this. If there is a runner at third base, a batter will often attempt a sacrifice fly, hitting a fly ball deep into the outfield, allowing the runner at third to 'tag up' after the ball is caught and run home to score. The other way is by bunting, which involves holding the bat horizontal to the ground over the plate and tapping the ball toward the ground, usually toward a baseline. If done correctly, this usually forces a fielder to get the guaranteed out at first, allowing any runners on base to advance. If done extremely well, a fast batter may be able to get on base himself.
UT's comment applies in that, for a modern fighter jet, missiles are definitely the preferred and most-often-used pieces of armament. Using a gun is only good at very close range in certain circumstances. That being said, there are a few situations where using the gun is not only well-advised, but absolutely necessary; doing so could save a pilot's life. An interesting side note here is that the A-10 Warthog anti-tank attack craft proves as an exception to this rule. While it does carry air-to-ground missiles, its primary weapon is an absolutely massive and stunningly rapid Gatling gun that fires depleted uranium rounds. Its entire design is based on being maneuverable at slow speeds and being able to take a withering amount of enemy fire while still making it home. The things have been used for the past 25 years, and as far as I know, they're scheduled to remain in service until at least 2035 or so. They may be ugly, but the people who fly them absolutely love them. If the F-16 is the Valkyrie of the fighter world, the A-10 is definitely the Herc.
Not that all of this has much to do with the original topic (and that didn't make much sense anyway), but I thought it still made for a reasonable explanation. I agree with UT, though; you Brits have no right to complain about unfamiliar terms when you subject us to reams upon reams of nearly indecipherable slang on a daily basis.
