Benjamin is also a
slang word for an
American 100-dollar bill.
This refers to the face of Benjamin Franklin, early American statesman and inventor, which is to be found smack dab, front and center on said bill (both before and after the recent redesign of all American paper currency).
The rapper/entertainer Puff Daddy had a hit, It's All About the Benjamins in the late '90s. See this song for more context in this usage of the term.