Every dog has his day - Idioms by The Free Dictionary
every dog has his day
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every dog has its day
Even the least fortunate person will have success at some point. I know you're shocked that that dopey kid got a better grade than you, but hey, every dog has its day.
every dog has his (or its) day everyone will have good luck or success at some point in their lives. proverb
every dog has his/its ˈday (saying) (often used to encourage somebody) everyone will, at some time in their life, be successful or lucky: They say every dog has its day, and mine is on Wednesday, when I will be interviewed for a television programme!