Two horses

Two blondes went to the market. While they were there, they each bought a horse. When they got home, they discussed how to tell their horses apart. They decided to cut the tail off of one. That worked for a while, but soon the tail grew back, so they decided that they would break one of the horses' legs. One of the blondes said, "Which of the horses should we break the leg off of, the brown one or the white one?"