Did you know President Trump invented the phrase "priming the pump?" He did so in the last few days, actually, according to himself:
[The Economist]: ... It's okay if the tax plan increases the deficit?[President Trump]: It is okay, because it won't increase it for long. You may have two years where you'll … you understand the expression "prime the pump"?
Yes.We have to prime the pump.
It's very Keynesian. We're the highest-taxed nation in the world. Have you heard that expression before, for this particular type of an event?
Priming the pump? Yeah, have you heard it?
Yes. Have you heard that expression used before? Because I haven't heard it. I mean, I just … I came up with it a couple of days ago and I thought it was good. It's what you have to do.
It's…Yeah, what you have to do is you have to put something in before you can get something out. [The Economist]
Trump has actually used the phrase "priming the pump" longer ago than just "a couple of days," such as this time in December:
And then there is the fact that The American Heritage Idioms Dictionary writes that "in the late 1800s, ['priming the pump'] originally was used for pouring liquid into a pump to expel the air and make it work. In the 1930s it was applied to government efforts to stimulate the economy and thereafter was applied to other undertakings."
Of course, the authors of The American Heritage Idioms Dictionary must be mistaken. The president himself says so.