The Merry Pranksters atop their bus, Further, getting ready to take LSD across America.

Date and location unspecified.

Ian Burt/Flickr Ken Kesey.

La Honda, California. 1971.

Robert Altman/Michael Ochs Archives/Getty Images Two women prepare for the Acid Test Graduation, a celebration organized by Ken Kesey and his Merry Pranksters, where people will be "awakened" by drinking LSD-laced Kool-Aid.

San Francisco, California. October 31, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images A young boy at one of Kesey's parties, high on LSD.

San Francisco, California. October 31, 1966.

Paul Ryan/Michael Ochs Archives/Getty Images Neal Cassady, the inspiration for Dean Moriarty from On The Road, stands with Gut, a member of the Hells Angels.

Both men have been lured into Ken Kesey's group of Merry Pranksters. Here, they are getting ready to take the magic bus Further to the next Acid Test.

San Francisco, California. October 30, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images The Merry Pranksters hop onto Further and head off to the next Electric Kool-Aid Acid Test.

San Francisco, California. October 30, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images A poster for Kesey's acid tests promises a chance to meet Beat poet Allen Ginsberg and features a photo of the poet in the nude.

Photograph of the poster taken in Prague, Czech Republic on April 3, 2008.

ex-Martin Hassman/Flickr Merry Prankster Doris Delay and a member of the Hells Angels dance together inside of Ken Kesey's test at the Acid Test Graduation party.

San Francisco, California. October 31, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images The Grateful Dead, the Merry Pranksters' house band for the Acid Tests, perform while Ken Kesey lights up in the background.

San Francisco, California. December 31, 1977.

Ed Perlstein/Redferns/Getty Images The Anonymous Artists of America perform at the Acid Test Graduation.

San Francisco, California. October 31, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images A woman high on LSD at an Acid Test can't stop gawking at the shirtless Neal Cassady.

San Francisco, California. October 31, 1966.

© Ted Streshinsky/CORBIS/Corbis via Getty Images A Hell's Angel and a hippie girl sit down and talk, both high on LSD at Kesey's Acid Test.

San Francisco, California. October 31, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images Ken Kesey speaks, his eyes bulging and his hands gesturing frantically.

Date and location unspecified.

Hulton-Deutsch/Hulton-Deutsch Collection/Corbis via Getty Images Merry Prankster Doris Delay dances at the Acid Test Graduation, having the time of her life.

San Francisco, California. October 31, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images Another woman at the acid test sits in the corner, apparently not sharing Doris Delay's high.

San Francisco, California. October 31, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images A group of partygoers sit around the couch, most experiencing LSD for the first time.

San Francisco, California. October 31, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images Neal Cassady hops on the magic bus, ready to follow the Merry Pranksters to the next Acid Test.

San Francisco, California. October 30, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images A Merry Prankster called "The Hermit" touches up the paint on the magic bus, Further.

San Francisco, California. October 30, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images Merry Prankster and author Stewart Brand sets up instruments on top of the magic bus.

San Francisco, California. October 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images The Merry Pranksters arrive at Woodstock with a school bus full of LSD.

White Lake, New York. August 1969.

John Dominis/The LIFE Picture Collection/Getty Images Two members of the Merry Pranksters talk to a member of the Hells Angels at one of their acid tests.

San Francisco, California. October 31, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images Ken Kesey poses for a picture with a young flower child.

La Honda, California. 1971.

Robert Altman/Michael Ochs Archives/Getty Images Merry Prankster Ken Babbs hangs out at Woodstock. This will be the magic bus' last trip.

White Lake, New York. Circa August 15-18, 1969.

Ralph Ackerman/Getty Images A man dances, high on LSD, at one of Kesey's acid tests.

San Francisco, California. October 31, 1966.

Ted Streshinsky/CORBIS/Corbis via Getty Images At Woodstock, a man eats lunch on the hood of the school bus.

White Lake, New York. August 1969.

Ralph Ackerman/Getty Images Ken Babbs, one of the Merry Pranksters, talks to a filmmaker interested in the acid tests.

White Lake, New York. Circa August 15-18, 1969.

Ralph Ackerman/Getty Images Years later, Ken Kesey takes Further out for one last ride, driving through the musical festivals of the new Grunge scene and bringing his Acid Tests to a new generation.

Seattle, Washington. September 1994.

Wikimedia CommonsAcid Test Hand Freakout The Electric Kool-Aid Acid Test: How The Author of “One Flew Over The Cuckoo’s Nest” Spread LSD Across America View Gallery

In 1964, Ken Kesey, author of One Flew Over the Cuckoo’s Nest, traveled across America in a tie-dye school bus with nothing but a few friends and enough LSD to get an entire country high.

He drove around America challenging people to take his "acid tests" — and thus helped start the entire hippie movement.

Strange though it may seem, this was all inspired by the CIA. Kesey had a part of their MKULTRA program, in which the CIA fed LSD and other psychedelics to citizen guinea pigs in order to see what would happen. For Kesey, the experience opened his mind and he wanted to share it with the world.

He set out with a group called the Merry Pranksters in order to conduct his acid tests with anyone that he could find. The group included beatniks like Allen Ginsberg and Neal Cassady, who inspired Jack Kerouac's On The Road. Kesey's house band was the Grateful Dead, then an unknown group called the Warlocks. And his journey was chronicled by author Tom Wolfe, who would immortalize the trip in his book The Electric Kool-Aid Acid Test.

These Merry Pranksters threw parties across the country, inviting people to try LSD and “graduate” into what they considered a higher order of thinking. All kinds of people got involved. Artists, musicians, and even members of the Hells Angels flocked out to Ken Kesey’s acid tests both to party and to become, as they would say, "aware."

But it was more than just that — it was a happening that changed the world. They passed LSD through the youth and the celebrities of the day and thus helped create a whole new era: the era of psychedelics, hippies, and rebellion.

It was a revolution. As Merry Prankster Ken Babbs told the BBC, "We won’t blow up their buildings, we’ll blow their minds."

Next, check out some of the most incredible Woodstock photos and see what life was like inside America's hippie communes. Then, read up on hippie history.

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