pluck something out of the air
idiomPart ofair
pluck something out of the air — idiom
1. To say a name, number, etc. without thinking, especially as an answer.
1.idiom
Definition
To say a name, number, etc. without thinking, especially as an answer.
Example
He plucked a random number out of the air.
When asked, she plucked a name out of the air.