I'm in tears.
He asks FOUR times if they've heard the expression before. Then he claims he just invented it. FOUR times. FOUR ******* TIMES. **** is wrong with him.
http://www.economist.com/Trumptranscript
In an interview with The Economist, President Trump explained how he coined the expression, which actually has been around since the early 19th century. According to Merriam-Webster, the definition of "prime (or priming) the pump" is "to take steps to encourage the growth or functioning of something."