In "A Fisher of Men" in Dr. Thorndyke's Case-Book by R. Austin Freeman, Dr. Jervis was digging the earth with his friend, while they saw a stranger man coming along the path, then that man was for the moment hidden from them by a bend of the path and a near clump of bushes.
At this moment the stranger reappeared, walking as if for a wager, and I began to peck up the earth with my pocket-knife.
I searched for its meaning, but I didn't find anything that I can understand in this context!