Originates from casino the
gambling term "
STACKS ON RACKS." Plastic "racks" hold "stacks" of 100 casino chips each. Since casino chips are uniform in size, a rack can hold $100 (if $1 chips) up to $500,000 (if $5,000.00 Chips). The "racks" themselves are also stackable. So RACKS ON RACKS describes the stacking of plastic chip racks....each holding stacks of up to 100 casino chips of any
denomination as described. AKA a shitload of money.