From Longman Dictionary of Contemporary Englishout to lunchout to lunchinformalCRAZY behaving or talking in a strange or crazy way → lunch
Examples from the Corpus
out to lunch• Round the bend, out to lunch.• And he has learned he still needs to go out to lunch occasionally, just to feel part of the business world.• We're going out to lunch or what?• I would be nice to her, see her, take her out to lunch.• Fisher took him out to lunch afterward.• He looked out to lunch - Mr and Mrs Sanity were clearly not at home to callers.• Two or three are always missing, out to lunch, or in the john, or wandering around the building.• Having explained carefully to Willis what he was about to do, Richard invited Pinkie out to lunch. 