come from left field

To originate from a surprising or strange place. ("Left field" is the metaphorical origin of something uncommon, unpopular, or otherwise strange.) That suggestion certainly came from left field! How did you come up with that one?

A question, statement, or event which comes from left field or comes out of left field is completely unexpected. The question came out of left field, but Mary Ann wasn't really surprised. This letter sort of came out of left field. Compare with left-field. Note: In baseball, left field is part of the outfield. A ball is said to come out of left field when the pitcher throws it in such a way that it seems to come out of nowhere.