Episode scene:

The Virginian, Trampas and Steve are anxious to get on their way back to Shiloh with some new livestock that have come in on the train. But the Judge has left orders that no cows are to be unloaded from the train until Wyoming's new senator finishes his speech. The Virginian tells a reluctant Steve to get planks - he will unload the bull, not the cows (thereby abiding by the Judge's orders) knowing it will stir up the cows left on the train. After patiently listening to the Virginian's flimsy excuse that he doesn't know how the bull got out, the Judge grants permission to unload the rest of the cattle, then smiles in amusement at his foreman’s prank.

The devilish twinkle in James Drury’s eye when he conceives this prank, and his child-like, but feigned, penitence afterward mesh perfectly with Owen Wister’s description of the Virginian (see below).

Quotation from the book (Chapter 10):

[The Virginian] now turned his eyes upon the collected babies wrapped in various colored shawls and knitted work....
“If they look so awful alike in the heavenly gyarden,” the gentle Southerner continued, “I’d just hate to be the folks that has the cuttin’ of ’em out o’ the general herd. And that’s a right quaint notion too,” he added softly. “Them under the chair are Uncle Hughey’s, didn’t you tell me?” And stooping, he lifted the torpid babies and placed them beneath a table. “No, that ain’t thorough,” he murmured. With wonderful dexterity and solicitude for their welfare, he removed the loose wrap which was around them, and this soon led to an intricate process of exchange. For a moment Mr. McLean had been staring at the Virginian, puzzled. Then, with a joyful yelp of enlightenment, he sprang to abet him.
...The women cried for vengeance...Mrs. Westfall argued long that punishment should be dealt the offender...“Yes,” spoke the Virginian in their midst, “that wasn’t sort o’ right. Especially as I am the man you’re huntin’....Come and kill me,” he continued, looking round upon the party. “I’ll not resist.” But they could not resist the way in which he had looked round upon them. He had chosen the right moment for his confession.

Additional comments:

1. In Chapter 21 of the book, the Virginian pretends to be disturbed by his sinfulness after a preacher, who is the Judge's guest, hurls fire and brimstone at the ranch hands. He keeps the preacher awake all night pleading for salvation, and in the morning tells him “I’ll worry through the day somehow without yu’. And tonight you can turn your wolf loose on me again.” [As the preacher storms away:] It was suddenly too much for the Virginian. He hastened into his room, and there sank on the floor with his head in his hands...I could hear the Virginian’s convulsions through the door... [Later, at breakfast the Judge hears the story of what happened and we learn that:] The ladies were inclined to be scandalized, but not the Judge...“I’d make him lieutenant-general if the ranch offered that position!” he declared.
2. See The Big Deal for another of the Virginian's pranks.