You should convince her that it came from Nurse Ratched
Was an existing concept long before the rise of "ratchet". Certainly lame enough of a pun to fit Kesey's slapping at the keyboard while high on LSD style of 'writing'.
http://www.cliffsnotes.com/literature/o/one-flew-over-the-cuckoos-nest/character-analysis/nurse-ratched
The name Ratched is also a pun of "ratchet," which is a both a verb and a noun for a device that uses a twisting motion to tighten bolts into place. This pun serves a greater metaphorical purpose in Kesey's hands, as Ratched manipulates the patients and twists them to spy on one another or expose each others' weaknesses in group sessions. The ratchet, as critic Ronald Wallace notes, is also "like a ratchet wrench she keeps her patients 'adjusted,' but like a ratchet, a gear in the Combine, she is herself mechanically enmeshed." The most comic reading of her name, however, is as a pun on the word "wretched."
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