(your) mind goes blank

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

I was so nervous during the interview that when I was asked about my experience, my mind went blank.

• the genie is out of the bottle
• the ghost at the feast
• the gift of the gab
• the glory days
• the glory days of
• the glory days of something
• the gloves are off
• the goggle-box
• the good old days
• the gory details
• the gospel truth
• the grand old man of
• the grand old man of something
• the grass is always greener .
• the grass is always greener on the other side of the fence.
• the grass roots
• the graveyard shift
• the gravy train
• the greasy pole
• the great and the good
• the greatest thing since sliced bread
• the green-eyed monster
• the Grim Reaper
• the groves of academe
• the hair of the dog