have the bit in (one's) teeth(redirected from have the bit in their teeth)
have the bit in (one's) teeth
To do something decisively and with resolve. A reference to a horse that is no longer under the rider's control because the bit (part of the apparatus used to guide it) is out of place in its mouth. Once Sophie has the bit in her teeth, she's the best student in my class.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.