1
general::
Certainly not, as in Go hang-gliding? Not on your life. The first recorded use of this interjection was in 1896. not open one's mouth Also, shut one's mouth;not say or utter a word. Be silent, repress one's feelings or opinions, keep a secret. For example, Don't worry, I'm not going to open my mouth on this issue, or She promised not to say a word about it to anyone. Also see HOLD ONE'S TONGUE; KEEP ONE'S MOUTH SHUT.
American Heritage Idioms