Спросил Грегга по поводу текста.
Вот что он ответил:
Another great song! The lyrics mean she has gone crazy, lost her mind… another way to say it is to “come unglued” as if everything that is supposed to hold her mind together is no longer there… and she’s come undun! Undun is a slang version of un-done.
Keep in mind when this song was written there was a lot of experimenting with LSD going on, and these lyrics could be referring to a “bad trip” or overdose from LSD, which gave the user hallucinations and made them look like they were not in their right mind. Sometimes the overdose would be permanent…I had a cousin, a very talented musician, who never recovered from taking too much LSD…he lost his job, became homeless, and walked the streets talking to himself and to imaginary people for years until he died. It was a shame. He came undun!
Таким образом, выражение She's come undun означает "Она сошла с ума", "Она свихнулась", "Она двинулась рассудком".
Ну и рассуждения про "бэд трип", ессно, для понимания картины.