You’re Saying It Wrong! Champing vs. Chomping
It’s champing at the bit, not chomping at the bit. This phrase (or idiom) comes from the sport of kings: horse racing. A bit is part of the apparatus that goes in the horse’s mouth and connects to the bridle and reins so the horse can be controlled and directed by the jockey on its back. The bit fits into a toothless ridge of the horse’s mouth, so the horse never really bites the bit.