To have another guess coming American phrase informal
The phrase is almost always preceded by "If (one) thinks (something)."
If someone "has another guess coming", he/she needs to reconsider or rethink something because he/she was wrong the first time.
If you think you convinced her of joining the year-end party, you've got another guess coming.
If she thinks she could misbehave like that in front of older people, she has another guess coming.
I assumed that you both knew each other before, but I need to have another guess coming.
The verb "have" should be conjugated according to its tense.
It dates from the first half of the 1900s. C. Day Lewis used it in Child of Misfortune (1939): “If you think that’s your doing, you’ve got another guess coming.”
Used to refer to a intelligent or smart person
If you're such a clever clogs, beat him in this chess game.