champ

champ at the bit and chomp at the bit 

1. Lit. [for a horse] to bite at its bit, eager to move along. Dobbin was champing at the bit, eager to go.

2. Fig. to be ready and anxious to do something. The kids were champing at the bit to get into the swimming pool. The dogs were champing at the bit to begin the hunt.

See also: bit

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be champing/chomping at the bit  also be chafing at the bit

to be very keen to start an activity or to go somewhere By the time he arrived to pick us up we were champing at the bit with impatience. I'm not sure if he's ready for extra responsibility yet, but he's chafing at the bit.

See also: bit

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champ at the bit also chomp at the bit

to be very eager The phone companies are champing at the bit to expand into these new lines of business.

Etymology: based on the idea of a horse chewing on the bit (piece of metal in its mouth that allows a rider to control its movements) when excited or nervous

See also: bit