Maker’s Mark’s iconic red wax seal makes it one of the most recognizable bottles on the brown liquor shelf. And it’s something Makers Mark takes very seriously.

Each bottle is hand-dipped in special-formula, molten red wax at its Loretto, Ky., distillery. The additional labor adds cost to production and slows output from an average of 200 to 400 bottles per hour to around 100 to 200 bottles per hour.

Occasionally, though, due to human error or something arguably more intriguing, bottles hit shelves doused in much more wax than usual. On these whiskies, known as Slam Dunk or Oops bottles, wax extends past the bottle’s shoulders and onto its label. The rarities are a collector’s item among whisky connoisseurs, often fetching double their retail value on auction sites such as eBay.

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Given the attention paid to the wax-sealing process — not to mention the countless hours’ experience workers amass dipping bottles — it’s hard to conceive that these bottles are the product of heavy-handedness or a momentary loss of concentration.

Comments on online forums speculate that slam-dunking is a clever marketing ploy used to keep whisky hounds hunting. Some suggest that around one in every hundred bottles is slam dunked, while others argue that number is much closer to one in a thousand. Even more outlandish theorists suggest that bottles are dunked every time a grain trolley goes by the finishing bottle line, e.g., about three to four times per day.

Maker’s Mark remains tight-lipped about the practice. When VinePair contacted the Kentucky distiller’s media representative about Slam Dunk bottles, they told us that they couldn’t report on the number of hand-dipped bottles.

Maker’s Mark does, however, acknowledge that over-dipped bottles exist. In a 2015 Twitter post featuring a photo of one such bottle, Maker’s Mark wrote: “When a bottle has a little extra wax, we call it a slam-dunk bottle!” The distiller has even run a number of ad campaigns alluding to the names collectors use for them.

“It’s not about the shots, it’s about the dunks,” ran the text on a poster featuring a bottle with a wax seal that runs all the way down to its label. Another, showcasing a completely coated bottle, simply said: “Alley-oops.”

For those not wishing to pay inflated prices on auction sites, the hunt for a Slam Dunk bottle can take years. On Dolcetto Confessions, the online blog of Allison Mannella, a self-described photographer, wife, and southern girl at heart, the author notes a “long, fruitless hunt” for a Slam Dunk bottle that lasted over two and a half years before she finally got her hands on one. (Manella also chimes in on the debate of just how rare these bottles are, writing that “only one in 824 bottles showcases the extra long layer of wax.”)

Don’t fancy that kind of wait? There might be another way to get your hands on a Slam Dunk bottle.

Each tour of Maker’s Mark’s distillery ends with the opportunity for guests to seal their own bottle. Wearing protective clothing, guests dip bottles into the 350-degree molten wax to a point just below a small indentation in the bottle’s neck (roughly a quarter of the way down).

Some, however, including this YouTube user, see this as a golden opportunity to create their very own over-dipped Slam Dunk bottle.

Though Maker’s Mark definitely does not advocate guests over-dipping bottles, the opportunity keeps some coming back for more. In a Chowhound forum on the topic, user JB BANNISTER writes: “I stop by twice a year and YOU CAN DIP YOUR OWN BOTTLE in the gift shop. I only do slam dunks as I use them for gifts.”

One might wonder if the “Mark” in Maker’s Mark is actually short for “marketing.”