not say boo to a goose

Meaning

1. to be very shy or gentle

   He's so nervous he wouldn't say boo to a goose.

From the same entry

• before you can say Jack Robinson
• go without saying
• have something, nothing, to say for yourself
• having said that
• I'll say
• I must say
• I say
• it says a lot, very little, for
• I wouldn't say no
• least said soonest mended
• the less said the better
• never say die