There is little more powerful than a nerd on a mission. Take the recent toilet paper gun for example, in which one nerd rigged up a leaf blower with some rolls of toilet paper:

But this isn’t even close to the nerdiest prank around. Even nerdier: the prank that A.T. Wilson played on Melvin Calvin. You probably spent hour memorizing the Calvin cycle at some point, and this is the Calvin you can thank. He set up a detailed and complex experiment that measured pH, oxygen, light and carbon dioxide during photosynthesis. His 1955 paper is a classic, and it features a detailed diagram of the setup.

Joshua Howgego explains where the prankster snuck into this diagram:

Wilson reputedly made a wager with his departmental secretary that he could sneak in a picture of a man fishing into one of the diagrams in a forthcoming paper without his supervisor noticing. He won his bet and the fishing man is still in the diagram today. Calvin never found out.

Here’s the fishing man:

Thankfully, the prank didn’t keep Calvin from winning a Nobel Prize for his work.

Or take these code names used by NASA:

Every Apollo astronaut knew the code phrases Navi, Dnoces, and Regor, which refer to the stars Gamma Cassiopeiae, Iota Ursa Majoris, and Gamma Velorum, respectively. This trio of stars was (and likely is) used for visual reference during spaceflight, and was a core component of Apollo mission training for inertial navigation procedures.

Those two-syllable code names, however, were a practical joke used by Apollo 1. Tech Republic explains:

Navi is Gus Grissom’s middle name, Ivan, spelled backwards. Dnoces is the word second spelled backwards, in reference to astronaut White’s full name, Edward H. White II. Regor is Roger Chaffee’s first name spelled backwards. Despite their snarky origins, Navi, Dnoces, and Regor stayed in the Apollo lexicon as an insiders’ tribute to the first three Apollo astronauts who gave their lives in service to NASA, the United States, and — above all — human discovery. While far from the first, last, or only tribute to Apollo 1, it is among the most fitting and sincere, as it came from Grissom, White, and Chaffee’s fellow astronauts and space program teammates.

Okay, what about the mystery package sent to the University of Chicago for Henry Walton Jones, Jr. (otherwise known as Indiana Jones)? The University of Chicago’s Admissions Tumbr writes:

The package contained an incredibly detailed replica of “University of Chicago Professor” Abner Ravenwood’s journal from Indiana Jones and the Raiders of the Lost Ark. It looks only sort of like this one, but almost exactly like this one, so much so that we thought it might have been the one that was for sale on Ebay had we not seen some telling inconsistencies in cover color and “Ex Libris” page (and distinct lack of sword). The book itself is a bit dusty, and the cover is teal fabric with a red velvet spine, with weathered inserts and many postcards/pictures of Marion Ravenwood (and some cool old replica money) included. It’s clear that it is mostly, but not completely handmade, as although the included paper is weathered all of the “handwriting” and calligraphy lacks the telltale pressure marks of actual handwriting.

They also have a few questions:

If you’re an applicant and sent this to us: Why? How? Did you make it? Why so awesome? If you’re a member of the University community and this belongs to you or you’ve gotten one like it before, PLEASE tell us how you acquired it, and whether or not yours came with a description— or if we’re making a big deal out of the fact that you accidentally slipped a gift for a friend in to the inter-university mail system. If you are an Indiana Jones enthusiast and have any idea who may have sent this to us or who made it, let us know that, too.

Eventually they found the package’s origins. It was, in fact, from an eBay seller who makes replicas of the Raiders of the Lost Ark Notebook. Although he’s not entirely sure how it got to the University of Chicago, he let them keep it.

And for on last geek prank: here’s someone at MIT who turned a building into R2D2. Or just look at Google every April Fools day.

More from Smithsonian.com:

Mark Twain was Secretly A Geek, and Here’s Footage to Prove It