Kicking something into touch, meaning to stop it dead, is one I would presume comes from rugby, where this is a common and deliberate part of play - although the ‘touchline’ also exists in football.
‘Pole position’ - does this originate with motor sport, or does it have an earlier usage?
That is a commonly used term in American football for when a quarterback is under pressure and unable to properly step forward in his throwing motion. He is said to be throwing off his back foot.
My guess is that this is more likely from boxing or earlier fighting. Getting pounded and pushed into a backward leaning position, and barely catching your balance with a foot put behind you.
I’ve never understood it (in the figurative usage) to mean something easy – I’ve always taken it to mean a “sure thing”, something as good as done. When the ball leaves your hand in an ordinary shot, it could still miss the basket; if you slam dunk it, there’s no chance of missing.
Actually, players miss dunks all the time, especially when they’re a) showboating, or b) not able to reach optimal dunking height. The opponent can also block a dunk.
Obviously, the percentage of dunks made successfully is much higher than for any other shot, except possibly the layup.
¿Como no? Por Favor!
Oh, well – if you’re going to muddy the waters with actual facts … 
I expect you’re right (what the hell would I know?), but on the other hand, I’m fairly sure most idioms aren’t rigorously fact-checked against statistics before use.
I expect I’m right too
And then there is sports slang that adds no meaning at all. Companies in the US no longer simply have plans, they have “game plans”, just like football teams.
In baseball, “caught him gazing” means the batter didn’t swing at strike 3. In real life, it means he missed something obvious, such as the cue to speak his piece, or the meaning of a joke. (whoosh)
Well, geez, there were only three posts at that point. Anyway, I read somewhere a long time ago that the term came from the Biltmore Hat Company giving out free hats to hockey players who scored three goals in a game. Anyone know if this is true?
We use “skunked” or “shut out” for that, although it’s mostly for sports–the first for individual sports, the second for team sports, generally. Pickup games here often have a “skunk rule” such that if the game gets to be too much of a blowout (5-0 in ping pong is the one I remember from my high school days), it automatically ends to save the loser from further humiliation and to keep from wasting everyone’s time. “Shut out” is used in TV broadcasts, most often in baseball and hockey, to refer to the act of preventing the other side from scoring throughout the entire game (noun form: “a shutout”). “Clean sheet” is another noun phrase for a shutout, mostly used of baseball pitchers. I know there’s something similar in soccer, though for the life of me I can’t remember what it is.
International, maybe. Obvious, not one bit.
I, for one, would like to hear them. (Make that two, I guess.)
I’ve always interpreted the use of “game plan” as adding the extra meaning that (1) the performance and cooperation of every team member is going to be essential, (2) there is limited time, (3) the plan is multifaceted, and (4) there is some kind of opposition, resistance, or adversity involved. You can make a plan for meeting your ex for dinner, but it’s not a “game plan” unless it’s going to be difficult to convince her to go or you intend to do more than have dinner (and she doesn’t).
I would suggest that “caught him looking” is more common. Of course, there are lots of other baseball terms that have achieved a high level of penetration into American culture as a whole and haven’t been mentioned here. To “swing for the fence(s)”, for example, means to try for “a home run”, or an overwhelming success. And of course, “grand slam” has seeped into international sports parlance, where it generally seems to involve winning four major tournaments in the same year or seasons. “Struck out” is another huge one, which has made “struck out on his/her own” quite confusing as a result. And some states, like California, have “three strikes” laws, where someone convicted of two violent felonies is given a life sentence on his third felony conviction, no matter what it is or how severe it is. Different indicators of adversity in the same situation are often called “strikes”, such that if I’m going to have trouble helping a student because she hates math and she doesn’t trust men, there are two strikes against me. Add another strike and it’s assumed that I have no chance of getting through to her at all. Then there’s “cover all your bases” and the less-common “hit for the cycle”, not to mention “rounding third” (being close to succeeding or completing a difficult task, often seduction), “the home stretch” (the last part of a difficult task or the end of a long time period like a school term or, if we’re going to go all meta, a sports season), “sliding [into] home [plate]” (completing a difficult task, often seduction), etc.
Really Not All That Bright, I’ve never heard of a “jabroni”, and I suspect that by “common parlance” you mean “[del]fake-sports soap opera[/del] pro wrestling fan slang”. It sounds like something a [del]fake-sports soap opera[/del] pro wrestling fan would say, anyway.