champ 1 
(chămp)
(chămp)v. champed, champ·ing, champs
v.tr.
To bite or chew upon noisily.
v.intr.
Idiom: To work the jaws and teeth vigorously.
champ at the bit
To show impatience at being held back or delayed. See Usage Note at chomp.
[Probably imitative.]