Chris mayo and the urge

This isn't an idiom because you can figure out what it means pretty easily. It's an exaggeration - pretending that your money is so eager to leave your pocket that it can burn a hole to get out.

This means that she can't wait to spend the money she has.

There is no clear origin to this phrase. In the 1700's, it was just used as "burning your pocket," but by the 1800's it had become "burning a hole in your pocket." The implication is that the coins are so hot that you jerk them out of your pocket and throw them away.