money shake
A hand shake where an exchange of money (usually a 20$ tip) is being concealed. The person giving the money will hold a bill in their palm. When that person goes to shake hands, the bill moves from one palm to the other in a smooth business transaction.
See the episode of Curb Your Enthusiasm where Larry David visits a restaurant and the regular host is accustomed to receiving a 20$ tip via the money shake. Later in the episode, David meets the host on the street and shakes his hand, forgetting about the 20$ bill he was holding. Larry David unintentionally preforms a money shake with the host.
shake money off his trousers
have so much money that one can give some to somebody on demand at once. The possessive adjective may be one's, her, my, our or their as the case may be.
He is so rich that he can shake money off his trousers.