out of thin air
US /aʊt əv θɪn ɛr/
UK /aʊt əv θɪn ɛr/

1.
de la nada, inesperadamente
appearing or happening suddenly and unexpectedly, as if from nowhere
:
•
The magician made a rabbit appear out of thin air.
El mago hizo aparecer un conejo de la nada.
•
Ideas don't just come out of thin air; they require effort and thought.
Las ideas no surgen de la nada; requieren esfuerzo y reflexión.