{not} [say] boo to a goose
1
to be very quiet and show signs of discomfort or anxiety when in public
The idiom "not say boo to a goose" is believed to have originated in Britain. The phrase originally referred to someone who was so timid or shy that they wouldn't even make a noise like "boo" to scare away a goose. It is used to describe someone who is exceptionally shy, timid, or introverted. It also suggests that the person is unlikely to speak up or take any action that might cause even a slight disturbance.
- He's the quietest person I know, he wouldn't say boo to a goose.
- His extreme shyness makes him appear as if he wouldn't say boo to a goose.
- She's so shy that she wouldn't say boo to a goose, even in a small gathering.