Or, Ooh, you dirty rat!
In fact, what Jimmy Cagney actually said in Blonde Crazy was "ooh, that dirty double-crossin' rat," which comment catalogues the crime that got poor old Ray Milland inextricably associated with the little-liked rattus rattus. It's the double-cross that makes you a rat. You're in on the swindle, but instead of playing straight, you queer the deal and roll over on your partner. Countless movies and TV shows have recreated the scenario in as many interrogation rooms. No honor among thieves when they put the screws to you, and compel you to cut a deal with the DA; less if you conspire with other blackguards for a bigger share of the swag.
Ok, so you know what a double-cross is. Now for a bit of likely etymological apocrypha, and the OED's version of events. The former is far more interesting, entertaining, and fun, and therefore likely to be utterly rubbish, but it's that kind of wonderful story that makes you really hope it's true. The latter is, by comparison, painfully bland.
So we'll start with that first.
The OED lists W.H. Ainsworth's 1834 poem "The Double Cross" as the first recorded usage of the term. As it's short and in the public domain, I'll chuck it down here:
Though all of us have heard of crost fights, And certain gains, by certain lost fights;
I rather fancies that its news, How in a mill, both men should lose;
For where the odds are thus made even, It plays the dickens with the steven:
Besides, against all rule they're sinning, where neither has no chance of winning.
Ri, tol, lol, etc.
Two milling coves, each wide awake, were backed to fight for heavy stake;
But in the mean time, so it was, Both kids agreed to play a cross;
Bold came each buffer to the scratch, To make it look a tightish match;
They peeled in style, and bets were making, T'was six to four, but few were taking.
Ri, tol, lol, etc.
Quite cautiously the mill began, For neither knew the other's plan:
Each cull completely in the dark, Of what might be his neighbour's mark;
Resolved his fibbing not to mind, nor yet to pay him back in kind;
So on each other kept they tout, And sparred a bit, and dodged about.
Ri, tol, lol, etc.
With mawleys raised, Tom bent his back, As if to place a heavy thwack;
While Jem, with neat left handed stopper, Straight threatened Tommy with a topper;
'Tis all my eye! no claret flows, No facers sound--no smashing blows,
Five minutes pass, yet not a hit, How can it end, pals ?--wait a bit.
Ri, tol, lol, etc.
Each cove was teared with double duty, To please his backers, yet play booty,
When, luckily for Jem, a teller was planted right upon his smeller
Down dropped he, stunned; when time was called Seconds in vain the seconds bawled;
The mill is o'er, the crosser crost, The losers won, the winners lost.
A fine yarn, that, but not quite matching the definition of double-cross as we currently understand it. The above suggests two individual "crosses," which makes for good farce but does little in the way of separating the arch-villains from the regular bad guys. For a true double-cross, they'd each have to know the other was in on it.
In 1848, in Vanity Fair, William Makepeace Thackeray uses the term "cross" to describe a fixed race. That's consistent with the above usage, so all's fair there. The double comes in when you put the word out that the fix is in, place a huge bet on what's now the short money, and then tell your man not to take a dive. Think Bruce Willis in Pulp Fiction. Instead of his ass goin' down in the third, he kills his opponent and collects big.
Less believable, but much sexier
As we all well know first recorded usage doesn't mean first actual usage. People have certainly been double-crossing each other for a lot longer than a couple of centuries. It makes sense to think they'd have come up with a clever way to accuse each other of doing it before 1870. So here's an alternate version of the term's origins:
In the first years of the 18th century, an English ne'er-do-well named Jonathan Wild did very well by running what is widely considered to be the first organized crime syndicate in the Western World. A truly glorified thief, Wild coordinated a bunch of lesser miscreants in a scam that encompassed all of London. His boys would nick your stuff, and he'd tell you he could get it back for you--for a very unreasonable fee, of course. Not that he kept any of it, you understand. Oh no. It was just necessary to grease the sticky hands that stole from you.
Eventually, Wild's net was cast so broadly that moving goods without his knowledge was nearly impossible and downright dangerous. It was not a good idea to cheese off a man known throughout the city as the Thief-Taker General. According to legend, here's what happened if you did.
Wild kept a ledger with all his cronies' names in it. If you annoyed him, failed him, looked at him funny, or slept with one his whores, you got an "X" (or cross) by your name. You did it twice, you got another--and Wild rid himself of you permanent-like.
There was a good side business to be had in turning known criminals over to the authorities in exchange for a bounty. If you were making a nuisance of yourself or if there was greater profit to be had from turning you in then keeping you on, down went the double-cross in the book and you were "'peached" to the millicents. Wild would count the money he earned by rolling you over as you took your last dangle at Tyburn.
This is the true double-cross as we know it today--one criminal turning in another for personal gain. Wild's accounting system seems a little convenient, and of course that magical ledger isn't exactly extant, so whether or not he used crosses, ticks, checks, hatches, or smiley faces can never be known. But what we've got is certainly better than "double-asterisked."
Pints of gin to: