As with anything in a casino, slot machines are designed to stack the odds against you. But what happens if you tweak the game to play to your advantage? Well, you'll probably end up in jail and/or Vegas's infamous Black Book, but plenty of people have deemed the risk worth it (this is gambling, after all). These 11 slot machine cheats range in cleverness, but they all have the same goal: Make as much money as possible.

1. Yo-Yo

This is the granddaddy of all slot machine scams, from which all others were born. Heck, even Donald Duck's nephew tried it in 1949. It's remarkably simple: The cheater ties a string around a coin and then places it in the machine until it registers a payment. They then yank out the coin and do the whole thing over again, "yo-yo'ing" with the same coin until they hit a jackpot (or get caught).

2. Shaved Coins

As technology advanced, manufacturers turned to optic verification sensors to prevent scams. These mechanisms use a beam of light to register payment as it's dropped in. Ironically, this technology was used against itself to perform a cheat very similar to the aforementioned yo-yo trick.

Intrepid ne'er–do–wells found that if a coin was slightly shaved around its edge, then a slot machine's optic sensor would register it as a normal coin. However, once it got to the machine's comparitor mechanism—the piece of equipment that measures size and weight—it would be kicked out because of the minute size discrepancy.

In many machines, the optic sensor worked independently from the physical comparitor mechanism. The former would be the sole judge of a coin's authenticity while the latter merely doled out change. Shaved coins were good for a play but would be returned in the change tray as bogus money—it's essentially the yo-yo trick sans string.

3. Fake Coins

What's better than shaved coins? Fake ones. Using advanced machinery, Louis "The Coin" Colavecchio pressed counterfeit slot machine coins out of hardened metal dies. These knock-offs were remarkable in their authenticity and passed for real at casinos all over Connecticut and New Jersey. You can watch a documentary about his scheme here.

4. Top-Bottom Joint

The top-bottom joint was an ingenious little tool used in the '70s and '80s to bilk slot machines. It consists of two parts: The "bottom," which is guitar string or similar wire, and the "top," which is a metal rod with one of its ends bent into a curly-q.

When the wheels spun into a winning position in older machines, a lever behind each wheel would slide into place. Attached to these levers were metal contacts, and when they aligned, they activated a circuit that powered the motor that dispensed coins. With the top-bottom joint, cheaters threaded the guitar string in through the machine's coin chute until they hit one of the metal contacts. They would then jam the "top" in through the coin receptacle. This would complete the electrical current and activate the motor, which would then barf out all the free coins they could handle.

5. Monkey Paw

Tommy Glenn Carmichael, known as one of the best slot scammers in history, was caught using a top-bottom joint in the mid-'80s and was sentenced to five years in prison. By the time he was released, slot machines had changed dramatically from clunky gear-and-lever devices to computer-controlled gizmos. Carmichael had to catch up, so he bought a video poker machine and used it as a guinea pig to test out his new inventions. The monkey paw, a device that took him six months to make, was probably the most effective.

For all the fancy technology that was added into machines, they still relied on some old-fashioned junk. The monkey's paw (or "slider") exploited this. The contraption was essentially a guitar or piano string attached to a bent metal rod. Carmichael would jam it into the machine through an air vent and fish around for the switch that released the coin hopper. The paw would then flick and activate the switch, and the machine happily spat out the dough.

According to Carmichael, he could make about $1000 per hour using the monkey paw before it became obsolete with the introduction of new kinds of machines. Naturally, Carmichael went back to work, and perfected his new invention, the...

6. Light Wand


Carmichael's light wand was nothing more than a battery-powered mini light attached to a wire. Newer machines used optical sensors to count how many coins they dispensed. The light wand would be inserted through the hopper and "blind" that optical sensor so the machine had no idea when to stop spitting out money. All you had to do was play enough until you hit a small payoff, switch on the light, and then wait for the machine to turn that modest return into a mountain of money.

7. Piano Wire

In 1982 at the Caesars Boardwalk Regency in Atlantic City, a group of men surrounded a slot machine on the casino floor. Each man had a job. One, dubbed the "mechanic," pried open the front and inserted 20-inch piano wires into the machine's whirring guts. He used the wires to jam the clock that timed each wheel's rotation. Because of this, he was able to manipulate and spin the wheels to his desired outcome.

After he forced the machine to hit a $50,000 jackpot, the mechanic departed from the scene, along with all the group's other members save for the man whose job it was to "win." Instead of congratulations, he got handcuffs. The entire scam was under surveillance by local authorities who were conducting a stakeout.

8. Bill Validator Device


This little device is often disguised to look like real legal tender. This camouflages two prongs that, when stuck into the bill validator, make the machine think $100 has been inserted.

9. Cheat Code


Ronald Dale Harris worked as a software engineer for the Nevada Gaming Commission and he was tasked with programming computer chips in slot machines. These chips calculated payouts and prevented tampering, but Harris secretly programmed his own code into more than 30 machines throughout Nevada.

The new code was downright brilliant. Harris made it so when someone inserted a specific combination of coins into the machine (E.g. three coins, wait, five coins, wait, one coin, wait, three coins) the machine would automatically pay out. His accomplices would enter the special coin combination into rigged machines around the state and reap the rewards. 

Harris wasn't caught until years later in Atlantic City, when his partner won $100,000 on a game of Keno. As a member of the Nevada Gaming Commission, Harris had inside info about the random number generator used in Keno and its source code. He was able to calculate what numbers were going to hit, and passed them along to his buddy. The resulting jackpot was the largest in New Jersey history for the game, and after an investigation, Harris' role was discovered—as well as clues leading to his slot machine cheat code racket. 

10. Computer Chip Replacement

"Slot machine jackpots—they are put there for people to win, and the casino expects to lose that money. And I arranged for that to happen," says Dennis Nikrasch, who reportedly made over $5 million from an ingenious slot machine cheat.

Nikrasch's grand scheme came about after he bought a computerized slot machine and tooled around with it in his garage. He found that he could manipulate the computer chip inside to give him a jackpot whenever he wanted. He ordered the standard chips from a manufacturer and made the appropriate alterations to them.

Nickrasch then organized a team and obtained keys on the black market that opened slot machines. At the casino, he would be able to open the slot machine, replace the chip, and dart out of the area in under three minutes. An accomplice would then stand in front of the doctored machine and take home the winnings.

11. Software Glitch

What happens if the cheat is built in? The Game King video poker machine was one of the most popular games in Vegas and other gambling hubs. It offered a variety of different kinds of poker, and featured big enough stakes to keep high rollers happy. It also had a glitch that could make you very rich.

The glitch was complicated, but it went like this: A player plays the machine at a low level—like $1.00 hands—until they win a relatively big payout. Before doing anything else, they switch to a new game on the same machine and play until they hit a win of any kind. A "double up" feature then flashes on the screen. (This entered the player into a double-or-nothing game of high-card draw.) To exploit the glitch, the player would put more money into the machine after the "double up" prompt and then switch back to the original game they were playing for $1.00. They would then up their stakes to the highest allotted amount and cash out. Their original winnings—that "relatively big payout"—would, upon cashing out, be multiplied by the new, much higher stakes. 

The men who discovered this trick were caught and tried on hacking charges brought by the feds. Those charges were eventually dropped, however, as the glitch was hardwired into the machines already.

All images courtesy of Thinkstock unless otherwise stated.