Make It Rain Meaning

(idiomatic) to throw a substantial amount of paper money so that it falls on a crowd, audience, performer, or group of performers, often as a way to show off one's wealth

Example:   It's time to make it rain, my friend!
  John has a propensity to make it rain at parties when he is drunk.
Used other than as an idiom: see make,‎ it,‎ rain.
  I asked higher powers to make it rain to save our crops.