from the GNU version of the Collaborative International Dictionary of English.
- Gamblers' Cant, U. S. A kind of gambling game consisting in pitching coins to or towards the ceiling of a room so that they shall fall as near as possible to a certain crack in the floor.
Sorry, no etymologies found.
In those times cattlemen played at crack-loo on the sidewalks with double-eagles, and gentlemen backed their conception of the fortuitous card with stacks limited in height only by the interference of gravity.
Then they would order three or four new California saddles from the storekeeper, and play crack-loo  on the sidewalk with twenty-dollar gold pieces.
[FOOTNOTE 25: Eighteenth Century mariners called the petrel (a large sea bird) "Mother Cary's chicken."] [FOOTNOTE 26: crack-loo -- a form of gambling in which coins are tossed high into the air with the object having one's coin land nearest a crack in the floor] "Was I on to the opportunity?