Or is it the one I beat for five thousand dollars? Thought he had 'caine but it was Gold Medal flour!
- Geto Boys, "Mind's Playin' Tricks on Me"
Selling a "beat" bag is a form of the Short Con that involves representing a bogus product as a more valuable, but illegal product, such as oregano for marijuana, baking soda for heroin, or cubic zirconias for stolen diamonds.
The buyer cannot report the scam to the police, because he doesn't dare admit he was trying to buy the illegal item in the first place. The main push on these is often that the deal has to go down fast, for cash, right now.
Very much a case of Truth in Television, since many jurisdictions treat drug supply as a more serious offence than fraud, and since street dealers are unlikely to see their mark again after the con. Note, however, that many jurisdictions make selling fake drugs carry the same penalty (and in some cases, make it the same crime) as selling the real thing in order to prevent Loophole Abuse. In some jurisdictions, for drugs that aren't considered very serious it might even be a WORSE crime to sell fakes, due to adulteration laws.
If the buyer sees the genuine article, but that's not what they get, it's Good For Bad. For cases where the scam is reported to the police, see Stupid Crooks.
Beat Bag is a subtrope of Pig In A Poke.
In the British Comic Viz, Paul Whicker (The Tall Vicar), responds to his verger's suggestion that the forthcoming youth group disco would give them the chance to 'shift some Es and whiz' with a grin and "Or aspirins and Vim if the ugly truth be known" (Vim being a brand of scouring powder with a (very) superficial resemblance to powdered amphetamine.
Dirk and his friends attempt this on Rahad Jackson in Boogie Nights. They might have gotten away with passing off talcum powder as heroin if a coked-up Todd hadn't gotten more demanding, causing the whole scam to go horribly wrong.
Performed in the movie Go, in which one of the characters sells harmless household products as drugs to inexperienced teens.
At the beginning of A Few Good Men, Kaffee is defending a client who bought and smoked "a dime bag of oregano."
Dave: Well, your client thought it was marijuana. Kaffee: My client's a moron, that's not against the law.
In Back to the Future, Doc Brown passes off a "shoddy bomb casing full of old pinball machine parts" to a gang of Libyan nationalists in place of a nuclear weapon, then scarpers with their plutonium.
This apparently happens a lot all the time to Mr. Tulip in the Discworld novel The Truth. "In a street where furtive people were selling Clang, Slap, Chop, Rhino, Skunk, Triplin, Floats, Honk, Double Honk, Gongers, and Slack, Mr. Tulip had an unerring way of finding the man who was retailing curry powder at what worked out as six hundred dollars a pound." Given he doesn't realize he keeps getting sold bags of household solvents, because snorting them doesn't seem to cause him any ill effects, it helps to show just how tough he is.
Moist von Lipwig enjoys playing these (usually with fake jewelry) in Going Postal. He doesn't find it too immoral, because upstanding, honest people generally doesn't fall for his con; the marks who do fall for it are generally people who try to take advantage of his seeming naivety, and just use the fake goods for their own scam in turn.
In Holes, X-Ray was arrested for selling drugs, but they turned out to be bags of chopped-up aspirin. Then he got arrested for selling aspirin without a pharmaceutical license.
Played with in Spaced, with the oregano-for-weed variant. They weren't out to con anyone originally - everyone involved thought it was weed. Daisy had just got confused earlier and put their weed in a stew, while Tim was unknowingly carrying a bag of oregano when they were mugged. When a catering student among the muggers interrupts their Fake High to point out what they're really smoking, they confront Tim and Daisy again, convinced that they'd been the victim of this con.
In The Pretender, a series where the No Social Skills protagonist does a Once an Episode thing of discovering something that people with normal childhoods take for granted, the episode "Silence" has him (A) discovering chocolate milk powder and (B) trying to bring down a drug pipeline transporting brown heroin. Near the end of the episode, he brings (A) and (B) together.
On My Name Is Earl, Earl and Randy wanted to take advantage of "special brownie night" at the Crab Shack. They switched the price tags on the brownies, so that those who wanted to buy the pot brownies ended up buying regular ones, and then Earl and Randy could sell the actual pot brownies later. Darnell intended to take the regular brownies to share with his mother, and is stopped by angry would-be stoners, who then proceeded to stone him. It was Biblical.
In the Raising the Bar episode "Is There a Doctor in the House?", Kellerman's client, a middle-aged woman, was arrested because the police found a large quantity of white powder in her car. . . while she was on the way to the laundromat. After lab tests confirmed that the powder was laundry detergent, the police showed their customary regard for the law by charging the defendant with selling a Beat Bag.
Shows up in The Wire when Bubbles steals a gang's ground stash, only to find the gang was selling vialed baking soda. He feels extremely guilty, having seen the gang beat up some innocent addicts for his theft as he was escaping. At the end of season four when Bubbles prepares a hot shot of cyanide for a fiend who constantly attacks him for money and drugs, expecting the fiend to take it, shoot up and drop dead. The effort fails when the fiend misses Bubbles during the day and Sherrod steals Bubble's stash that night, shooting up with the vial filled with cyanide.
Downton Abbey: During post-war rationing, Thomas tries to get into the black market by buying a stock of smuggled food, but it turns out to be inedible.
On the American version of The Office, Michael tries to frame Toby for drug dealing by planting marijuana on him. He tries to buy some from the warehouse guys and they sell him a bag of salad at a ridiculous price. For bonus points, it looks nothing like marijuana.
One American sitcom had the older sister pull this on her younger brother. She was a former delinquent that was making up for it. However her younger brother wanted some Ectasy for a party. She was going to tell him off, but then got a Imagine Spot of him dying from getting bad ecstasy from a drug dealer. So she gave him midol and told him it was ecstasy.
In The Brig Society, Marcus Brigstocke describes smoking oregano as a teenager because he didn't want to admit he'd been conned. "It didn't get me high, but it did give me the munchies." He also described doing this without any intent to con on the part of the other person, like buying the perfume Opium because he thought it contained actual opium.
In The Venture Bros., when Doc Venture was in college (with several other characters), Baron Underbeit gave another friend oregano to smoke claiming it was a rare drug from his homeland. Turns out the poor sap was allergic (which Underbeit didn't know at the time).