As can probably be gleaned from the writeup at A-side and B-side, audio recordings used to be made in their heyday by writing an analog signal on the walls of a groove in the surface of a thin vinyl disk. Such a groove could be etched into each side, so that each contained half of the total information. One side was played by rotating the disk under a stylus which rode in the groove, from the outer edge 'round and 'round until reaching the center. Then, to hear the other half, one would lift the stylus off the disk (called a "record", accent on the first syllable), lift the record and flip it over, put it back on the rotating bed (called the "platter") and lower the stylus at the periphery again.
(Though I once owned a record player that had a slot you put the record into, and inside the box it had a separate tonearm/stylus for each side so the record could be played in its entirety in one go.[1]. This was nice for all types of music, but especially so for symphonies that might take up the entirety of the record.)
Such a two-dimensional (essentially) object is easily pictured in the mind, and the method of use also. Thus people were astounded when a record was published claiming to have three sides! How could such a thing be? I don't think anybody thought an extra second or two of sound would have been recorded in an additional groove on the edge of the disk.
Those who just had to know could find out by purchasing a copy of it at the local record store. (Or maybe from Columbia House.) Most of the buyers, though, were undoubtedly fans of the British comedy troupe which went by the name Monty Python. In particular, they bought The Monty Python Matching Tie & Handkerchief, a dandy sartorial set of yellow circles on a red background, which happened to include in the box a 33 1/3 LP[2] record. (The label in the center of the record even said FREE RECORD.)
Most were confused when they found what appeared to be an ordinary record with two sides. They put in on their player and laughed at the skits, but nonetheless were nonplused: where was the third side?
At least a few listeners probably divined the deception, while it dawned on the majority when on their second (or maybe third, or tenth) time listening, they found that the content was different than on the first hearing. And after investigation, got another laugh upon discovering that one of the two sides actually had a second spiral groove inside of the first! Which one was played depended on where on the periphery the stylus was initially lowered: half of the circumference would catch the first groove and the other half would land in the second. (Of course, the total recording time was not increased by having two grooves.)
As a teen, I mightily enjoyed the prank. Too bad my copy is decades gone, as I see it selling on amazon.com for USD 121.
[1] Not only could it play both sides, but it had buttons on the front that allowed you to seek directly to any of the tracks. It could do this because the tonearm included a laser which could detect the short unrecorded lacuna between each selection.[3]
[2] The number indicated the rotational speed required to play the recording correctly, in RPM. LP meant "long playing". LPs could have six or seven songs on each side, while the original 45s (much smaller) only had one. While the smaller records were known as "45s", an LP was never referred to as a "33 1/3". (And why it couldn't have been just 33, I don't know.) I don't know if the predecessor of the 45, which played at 78 RPM, were known as "78s" when they were in vogue, but by the time I was born, they were.
[3] There was a television show once called "That's Incredible!", which had people exhibiting odd talents. My favorite was a man who could recognize, with good chances of being right, what the music was by looking at the surface of the record. I was able to do that with one: the Violin Concerto in D by Tchaikovsky.
Side Quest 2024