The year was 1977 and the U.S. was caught in the throes of a pop culture phenomenon unlike anything it had seen before, all because of a little movie called Star Wars. The Topps Company, known for making pocket-sized stacks of popular baseball players since the 1930s, lucked out when Kenner's subsidiary Donruss passed on the Star Wars license. What followed was one of the most successful series of trading cards ever created.

Five sets of cards and stickers were produced over the course of two years. In a time before the Wookiepedia, these were one of the few ways to get in-depth information about the beloved soon-to-be franchise. But the original editor of those cards, Gary Gerani, and his team made one small mistake that will go down in history.

They printed a card with a robot's penis on it.

"One of the most famous (or infamous) cards in all of Topps history has to be the one you're staring at right now," Gerani writes in Star Wars The original Topps Trading Card Series: Volume One.

"Notice anything unusual? I didn't. And neither did anyone else at Fox or Star Wars Corporation."

Gerani's team was moving so fast, scouring as many on-set photographs as they could get their hands on to flesh out the 330 card series, that they hardly noticed this truly bizarre shot of C-3PO getting into an oil bath on Tatooine. The internet's official arbiter on hoaxes, Snopes, quoted the official Star Wars website in 2007 as saying the photo is, in fact, theirs (although the link is now dead).

"[I]t appears that the extra appendage is not the work of an artist, but rather a trick of timing and light," Snopes quotes. "The untouched archive photo shows the image just as it appears on the card. The current theory is that at the exact instant the photo was snapped, a piece fell off the Threepio costume, and just happened to line up in such a way as to suggest a bawdy image."

Right. Gerani has another theory.

"Apparently someone on set strapped a long metallic appendage to the droid's lower half," he writes. "Was this an off-screen practical joke? And how, exactly, did the image make it into the photo archive? No one knows for sure, but once this curious anomaly was brought to light post-printing, some form of correction was required."

You can still find goldenrod's golden rod on eBay, where it's been framed under archival glass for easy addition to your home or office. But Gerani says that the airbrushed version which removed the offending member, executed by Topps company staff, is actually the more valuable print.

Weighing in at around 550 pages this collector's book — due out this November from art book publisher Abrams — is filled with rare insights from one of the first men to dive deeply into the Star Wars lore for fun and profit. The elegant book comes with a pack of reproduction cards, and is even wrapped in a wax-lined dust-jacket just like the original cards. Volumes two and three, featuring complete reproductions of the Topps trading cards for Empire Strikes Back and Return of the Jedi, are due out in 2016.