From Longman Dictionary of Contemporary Englishhow come?how come?REASONused to ask someone why or how something happened How come you’ve ended up here? ‘Last I heard, she was teaching in Mexico.’ ‘How come?’ → come
Examples from the Corpus
how come?• "I didn't even eat lunch today." "Really? How come?"• "She's moving to Alaska." "How come?"• And those bushy eyebrows that resembled dark clouds on his horizon.-How come?• How come he's asked us to spend all this money and not them?• How come I can't make her happy, how come she can't make me happy?• How come Mrs Wall-Eye know my name?• How come the sky is blue?• How come the vast majority of the population appears to want to play make-believe?• How come Tyler's still here?• How come you got back so early?• How come you never asked me what happened?• Joey, how come you never sweet-talk me in person?how come?how come?informalREASON used to ask why something has happened or why a particular situation exists, especially when you are surprised by it How come Dave’s home? Isn’t he feeling well? → howExamples from the Corpus
how come?• How come he's asked us to spend all this money and not them?• How come I can't make her happy, how come she can't make me happy?• How come Mrs Wall-Eye know my name?• How come the vast majority of the population appears to want to play make-believe?• How come you never asked me what happened?• Joey, how come you never sweet-talk me in person? 