take the bit in one's mouth

Also, take the bit between one's teeth. Throw off restraints and proceed on a headlong course, take control. For example, My partner took the bit in his mouth and bid a grand slam, or Jane took the bit between her teeth and now there's no stopping her. This idiom alludes to the bit, the metal mouthpiece of a bridle whereby a rider controls a horse. [c. 1600]

Words nearby take the bit in one's mouth

take something, take something on faith, take steps, take stock, take stock in, take the bit in one's mouth, take the bitter with the sweet, take the bread out of someone's mouth, take the bull by the horns, take the cake, take the edge off