An opposite to a "George" is a "stiff," i.e., a lousy tipper, the term having originated back in the late '30s in the restaurant trade, presumably in the context of its also being slang for a corpse. But you were asking about player parlance for losers. Bad tippers are also known as "Tom" (for reasons that escape us).
The first term that comes to mind for a sucker or loser is "fish," of which it is frequently said that if you can’t spot the fish at the (usually poker) table, you are the fish. You might also be termed a "pigeon," "rabbit," "lamb," "tuna," "turkey," "apple," "egg," "cucumber," "hayseed," "mooch," "square," or "mark." "Monkey" or "lobster" tends to be used specifically for a victim of cheating, and "fish betting" is mindlessly making the same wager over and over, while a "chump" is someone who's ripe for the picking, and a "donkey" or, more colloquially, a "donk," is an inexperienced player at the poker table. Borrowed from the dictionary of pimp slang, a "trick" in the context of a poker room is a poor player or sucker.
When the term "tourist" is used in Las Vegas cardrooms, it refers to someone who doesn’t live in Las Vegas and is therefore presumed to be at a disadvantage in to the savvy "local." If someone refers to you as an "Elmer," that’s short for "Elmer Tucker," rhyming slang (a British convention) for sucker, while "live one" is used in reference to a very loose poker player, usually implying a rich sucker who loses. His close cousin is the "maniac," a player who keeps betting regardless of whether he’s holding a good hand or not. Getting "soaked" is slang for losing badly and if you’re "cold," you’re experiencing a long losing streak. Experience an especially bad beat at the poker table and you've been "cold-decked" or "coolered."
The player you think is the fish but who is really a good player waiting to strike is a "shark." In a slight variant, professional-level players (especially in sports betting) are known as "wise guys" or "sharps," an abbreviated version of the old term "card sharp," which used to have pejorative connotations. "Grifters" are out-and-out cheats, as are "mechanics" and "crossroaders."
Found mainly in the slot realm, although also an inhabitant of sports books, is the "flea," a generally annoying guy who wants to be comped for low-roller play. Gamblers who just can’t help themselves are "degenerates" or, less pejoratively, "mopes." If they’re chasing their losses, they’re "on tilt" or "unglued;" if simply pushing their luck and "letting it ride,", they’re "pressing." If pressing doesn’t work, you’re going to wind up "tapped out" (a term shamelessly appropriated by mixed martial arts). Out-and-out naifs are known as "squares." And a wager on a game like Sigma Derby or the Big Six Wheel that has a significant house edge is a "sucker bet."
To persist in wagering when you’re on a losing run is to "chase," while those players without the sense to fold bad hands are "pay stations" or "calling stations." Small-timers are "ribbon clerks"; fold too often and you're "weak" while if you’re playing with "scared money," that’s cash you can’t afford to lose. The player at your poker table who mostly raises or folds but seldom calls, thereby playing very few hands, is a "rock." Get a whole bunch of them at one table and you have a "rock garden." If one of them sticks in to the bitter end despite holding a weak hand, he’s a "stonewall." If you max out your entire casino credit line, the employees will describe you as "burned out." Casino workers will also refer to the "i-factor" or "idiot factor," meaning the poor play of most gamblers that bolsters the house edge at a game.
In the sports-betting world, "the public" is used by pros to refer to the ignorant masses who bet with their hearts instead of their heads and if you bet only on favorites you’re a "chalk player." If you’re AWOL because you lost all your money, you’re "dry-holed." If you’ve got the money but simply refuse to pay, you’re a "mush artist" (one of several wonderful British colloquialisms) or a "welch." Either way, you’re likely to be on the business end of someone’s fist. A "mush" (pronounced "moosh") on the other hand, is a gambler who’s considered to be bad luck. The same, specifically in California card rooms, goes for a "black cat."
In blackjack (and other table games), a "ploppy" or "duffer" is an uniformed gambler; on the other hand, a skilled manipulator of the craps dice is known as "an arm." A "guerilla" or "gully," conversely, is an older term applied by professional gamblers to those who "skin the suckers." As comp wizard Max Rubin says, when something's just wrong with a player, he's "janky." And if you're advantage player extraordinaire James Grosjean, the unschooled general public are all simply "citizens."
As with all jargon and slang, new terms can pop up all the time and as you can see, there are already diverse terms applied within the context of different games and different countries. So, if you happen to know of a term we've missed, drop us a line!
