From Zappa Wiki Jawaka
Friendly Little Finger (04:17); 1975, recorded in a dressing room at Hofstra University and over-dubbed at the Record Plant, Los Angeles, California; originally released on the Warner Brothers album Zoot Allures; [...] This is one of the earliest examples of a technique I developed called Xenochrony (strange synchronizations). Other examples include "Rubber Shirt" on Sheik Yerbouti and every guitar solo on Joe's Garage except "Watermelon In Easter Hay". In this technique various tracks from unrelated sources are randomly synchronized with each other to make a final composition with rhythmic relationships unachievable by other means. In ordinary polyrhythmic terms we speak of 5 in the space of 4, or 7 in the space of 6. In Xenochrony we deal with larger units of time; a complete solo at one metronomic rate in the space of a track at another ... sort of like Monday and Tuesday crammed into the space of Wednesday. The solo and drone bass was recorded on a 2-track Nagra, 15 ips, with a pair of Neumann U-87 microphones in a rather wet-sounding dressing room, warming up before a concert at Hofstra University on Long Island. This pair of tracks was later Xenochronized to a drum track out-take from "The Ocean Is The Ultimate Solution". The introductory orchestration was added next, and then the Hofner bass (recorded at half-speed), rhythmically splitting the difference between the two different track tempos.
Zappa dubbed the technique "xenochrony," from the Greek words xeno (strange or alien) and chrono (time). As he explained, "In this technique, various tracks from unrelated sources are randomly synchronized with each other to make a final composition with rhythmic relationships unachievable by other means." For example, in the case of the Zoot Allures track "Friendly Little Finger," the solo guitar and bass were recorded in a dressing room on a 2-track Nagra and then later combined with an unrelated drum track for a piece called "The Ocean Is The Ultimate Solution," with additional instrumentation scored to complement the newly produced time signatures. Xenochrony proved to be a powerful new compositional tool for Zappa, and he returned to it many times over later albums.
Well, a classic "xenochrony" piece would be "Rubber Shirt", which is a song on the Sheik Yerbouti album. It takes a drum set part that was added to a song at one tempo. The drummer was instructed to play along with this one particular thing in a certain time signature, eleven-four, and that drum set part was extracted like a little piece of DNA from that master tape and put over here into this little cubicle. And then the bass part, which was designed to play along with another song at another speed, another rate in another time signature, four-four, that was removed from that master tape and put over here, and then the two were sandwiched together. And so the musical result is the result of two musicians, who were never in the same room at the same time, playing at two different rates in two different moods for two different purposes, when blended together, yielding a third result which is musical and synchronizes in a strange way. That's xenochrony. And I've done that on a number of tracks.