A Montana slang term for someone from California. Used in a derogatory sense. Many people from California do not know that Prunes are dried plums. You pick a plum.
We saw him in the bar with his new Stetson. We knew he was a Prune Picker because we saw him get out of the Lear at the Bozeman airport.
by Robert J. Lanier from Susan at Trader Joes, both from Montana March 15, 2007