A farmer and his brand new bride are riding home in a wagon pulled by a team of horses, when the older horse stumbles.
The farmer says: "That's once." A little further along, the horse stumbles again. The farmer says:
"That's twice." When the old horse stumbles again, the farmer quietly reaches under his seat, pulls out a shotgun, and shoots the horse.
His brand new bride yells,
"That was an awful thing to do!" The farmer says:
"That's once!"