LAST STRAW: a gota d'agua
The last of a series of annoyances or disappointments that leads one to a final loss of patience, temper, trust, or hope.
E.g.: It was the third time Johnny hadn’t done his homework, so the teacher lost her temper and said, “That’s the last straw! I’m going to call your mother!” – Era a terceira vez que Johnny não fazia a tarefa, então o professor perdeu a paciência e disse, “É a gota d’água! Vou ligar para sua mãe!”