Dead Presidents is a "street" term for cash money. Obviously, this is drawn from the images of the "dead" US Presidents found on most US Currency ($1 George Washinton, $2 Thomas Jefferson, $5 Abraham Lincoln, $10 Alexander Hamilton, $20 Andrew Jackson, $50 Ulysses S. Grant and $100 Benjamin Franklin). When most of us really want to get "paid in full", we're after a specifc kind of Dead Presidents aka "Benjamins" referring to Benjamin Franklin who is on the $100 bill. The irony here is that Benjamin Franklin, while a great man, was not a US President and neither was Alexander Hamilton (on the $20).
We gonna rob us a bank, and make off with some dead presidents.