In Reply to: Five spot posted by Jospec5Star on September 14, 2008 at 16:43:
: What is the origin of five spot or ten spot? It is a way of asking to spot money or borrow money?
: Ted: Can I get a five spot from you?
: Gina: Sure thing Ted. $5 coming your way.
It's an American usage, and just means a bill of that denomination in dollars, regardless of how it's used. Without context, a five-spot, for example, or a fiver, would mean money in that denomination. You could also have a ten-spot or a tenner, but you would probably not hear anyone speak of a hundred-spot or a hundreder (which is a C-note), nor a fifty-spot or fiftier. That normally would be called "a fifty," just as there's no twentyer, but rather "a twenty." "Twenty-spot" has been heard, but is probably somewhat rare.
I don't know why "spot," although it could be thought of as analogous to the (e.g.) five-spot playing card, which actually has five pips.
According to the OED, the expression has been in use at least since 1846.