Balled Up

I suppose we all ought to know by now that when you're trying to puzzle out the origins of words and idioms, the first thing you think of is almost certain to be wrong, however plausible it may sound (which explains the overabundance of ludicrous folk etymologies).

A couple of days ago, Slate.com published an explanation of the expression "balls to the wall", which had been used by an American politician the day before. They swear that "it has nothing to do with hammers, nails, and a particularly gruesome way of treating an enemy", which is reassuring, I suppose, but it also never even occurred to me, and thanks for the image, Slate. I did, however, think the balls in question were human; why exactly they were pressed against the wall (was the man being frisked?) and what that would have to do with the expression's actual meaning, which is "unrestrained: full-throttle", I have no idea. But that's what I assumed.

Wrong! Depending on who you ask, it has something to do with very fast machines. I'm not going to go into all the details here, particularly since nobody can agree on exactly what balls we're talking about, but you can read Slate's version, and then a few explanations on Idiomsite.com, and then the explanation given by the Mavens, and try to work it out for yourself.