On April 1 of each year since 2001, ThinkGeek, the online retailer, has devoted its home page to products that don’t exist. The names sound unlikely — Squeez Bacon, Surgestix Inhalable Caffeine Stix, p-Teq’s USB Pregnancy Test Kit, etc. — but they are presented as any item on the site would be: catalog description and list of features, pictures, maybe a video, price, “Buy Now” button. Click that and . . . ThinkGeek wishes you a happy April Fools’ Day. The joke is on you for believing that someone is making and selling a Betamax to HD-TV Converter.

The funny thing about ThinkGeek’s prank products, however, is that sometimes they do get made and sold, basically because the public demands it. The most recent example is the Tauntaun Sleeping Bag, which appeared on the site last April 1 as a gag and earlier this month went on sale for real, at $99. The item recalls a scene in the film “The Empire Strikes Back,” in which Luke Skywalker is freezing to death on the frigid planet Hoth, and Han Solo saves his life by slicing open the stomach of a dead Tauntaun (which is a sort of giant, ridable horse-lizard) and stuffing him in among its warm guts. The sleeping bag has a cute Tauntaun-head pillow, and its lining is printed with an intestine-like pattern. It’s absurd, but if you remember the scene from the movie, it’s also pretty much irresistible. Thus a lot of ThinkGeek’s customers, fooled or not, didn’t simply want to appreciate the funny idea of a Tauntaun sleeping bag. They wanted to own one. And said so in tens of thousands of e-mail messages and phone requests.

There were precedents. In 2007, the site’s phony products included the 8-Bit Tie, which is a goofy clip-on meant to look like a crude rendering from a video game and obviously too silly to wear in real life. But when it became clear people would really buy them, ThinkGeek really sold them — and sells them still. Last year its April Fools’ lineup included the Personal Soundtrack Shirt, with a speaker built into the front so you can blast “Back in Black” as you dramatically enter the room. Asinine. And now: real.

Image Credit... Bottom: Photograph from Thinkgeek.com

The Tauntaun sleeping bag’s back story is more complicated, because it’s a product that ThinkGeek was quite serious about selling from the start. Mostly a retailer, ThinkGeek does very little licensing and manufacturing, and its attempts to get a meeting with Lucasfilm to work out the rights to make the sleeping bag went nowhere. “We’d really pretty much given up,” Ty Liotta, the company’s senior merchandiser, said. “We decided: ‘We’re not doing anything else with this, and it’s funny. Let’s make it an April Fools’ product.’ ”