(your) mind is a blank

(your) mind goes blank - if you are asked a question and your mind goes blank, you cannot think of anything to say.

I can't even tell you what his name was - my mind's a complete blank.

• the real McCoy
• there and then
• There are no flies on .
• There are no flies on someone.
• There are plenty more where that came from.
• There are plenty more where they came from.
• There but for the grace of God .
• There but for the grace of God go I.
• Thereby hangs a tale.
• the received wisdom
• the red-carpet treatment
• the red-light district
• Therein hangs a tale.
• There is more to someone than meets the eye.
• There is more to something than meets the eye.
• there is never a dull moment
• there is no such thing
• there isn't a [mean, jealous, unkind etc.] bone in body
• there isn't a [mean, jealous, unkind etc.] bone in someone's body
• there is safety in numbers
• there'll be hell to pay
• there's a lot to be said for
• there's a lot to be said for doing something
• there's a lot to be said for something
• There's a time and a place.