make it rain

Short definition from Wiktionary

Verb

1. 1
   To bring prosperity or work to an enterprise by selling, inventing or other productive or successful activity.
2. 2
   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.
3. 3
   Used other than figuratively or idiomatically: see make, it, rain.