The deadliest just got easier to find.

Fentanyl, the synthetic opioid driving the overdose epidemic, is being offered for sale on Craigslist.

Craigslist has long been like America's back alley, and drugs ads often slide by without the moderators noticing. They're from weed dealers mostly, but also, sometimes, ayahuasca shamans, LSD-dosing Deadheads, kratom vendors and more.

But author Sam Quinones seemed shocked to find fentanyl available for sale on Craigslist in Los Angeles this week. In fact, Craigslist has become a "major new marketplace for illicit fentanyl," Quinones writes. Quinones is the author of the book "Dreamland: The True Tale of America's Opiate Epidemic," about an Ohio town torn up by opioids.

Fentanyl is a prescription drug, used on ambulances as a painkiller. It's incredibly concentrated — 50 to 100 times more potent than heroin — and so it's easy to distribute and hide.

Fentanyl is also the scariest thing going; just this month, authorities said that fentanyl surpassed heroin as the substance most often involved in overdoses deaths. Fentanyl is also showing up in strange places, like cocaine and maybe molly, for reasons no one understands.

On Craigslist, fentanyl dealers often use code words like "China white doll" or "white china plates." Fentanyl is a white powder, often made in China. Sometimes sellers will come right out and say they have "fenty fent."

screenshot - craigslist ad for fentanyl

[Screenshot from a Craigslist ad currently offering fentanyl in Los Angeles.]

"You're here because your guy is slow, and you're online looking to find some really good quality Fine China Dishes for sale," one ad reads.

Los Angeles is one of the crossroads for opioids, which come both from Asia and from Mexico. Craigslist dealers there have long sold heroin on the site, calling it "roofing tar."

Why is fentanyl showing up now? A heroin addict tells Quinones that fentanyl might be on the upswing because a local heroin delivery service called Manny's got busted.

Also, the addict told Quinones, "There's a lot of people who are choosing to use fentanyl."

[Cover photo: Fentanyl in prescription bottles. From Shutterstock.]