quaking/shaking in your boots/shoes

quake in (one's) boots

To tremble with fear or nervousness. (Sometimes said sarcastically.) My brother is so strong and scary-looking that people quake in their boots when he threatens them. Ooh, I'm really scared of you! I'm quaking in my boots, you frighten me so!
See also: boot, quake

(be) ˌquaking/ˌshaking in your ˈboots/ˈshoes

be very worried or frightened: The prospect of facing the team again in the semi-final had everyone quaking in their boots.
See also: boot, quake, shake, shoe