quail

An animal that quails is one that has a small and delicate body with usually brown feathers.

When we talk about something making someone quail, we often mean it's scary or intimidating. For example, "The thought of public speaking made her quail." It can also mean to feel faint or weak in the knees when faced with something unpleasant. If you've ever heard someone say that a movie was so bad it made them quail, they're probably being sarcastic and saying it's really bad.