Off One's Trolley Meaning

(informal, humorous, idiomatic) Having gone mad; insane.

Example: 1919: American Guild of Organists, American Organist, volume 2, page 409
  The Romance is the best part of the four movements. One is a bit off one’s trolley at such times and I should surely write a better Suite at this time after twenty years of sober reflection.
1915–1981: Kenneth Burke [contrib.], Malcolm Cowley [contrib.], and Paul Jay (editor), The Selected Correspondence of Kenneth Burke and Malcolm Cowley, 1915–1981, page 302 (1988; Viking; ISBN 0670813362, 9780670813360)
  On the whole, bodily symptoms have at least the consolatory fact about them, that they replace mental symptoms, fears of going off one’s trolley; and I suppose that, if I got rid of all the physical symptoms, things would but have been cleared away for a new worry about mental ones?
2006: Mike Ollerton, Getting the Buggers to Add Up, page 164 (Continuum International Publishing Group; ISBN 0826489141)
  Being slightly off one’s trolley
Uppermost in my list of top four teaching behaviours is being ever-so-slightly crazy ... to keep students guessing whether or not I have lost my marbles, and being not quite so predictable.