Horses

Lewis bought two horses, and could never remember which was
which. A neighbor suggested that he cut the tail of one horse
and that worked great until the other horse got his tail
caught in a bush. It tore just right and looked exactly like
the other horse's tail and Lewis was stuck again.
The neighbor suggested he notch the ear of one horse. That
worked fine until the other horse caught his ear on a barbed
wire fence. Once again Lewis couldn't tell them apart.
The neighbor suggested he measure the horses for height.
When he did, he was very pleased to find that the white horse
was 2 inches taller than the black one.

Thanks to TZ at Laffaday. The Lewis he refers to is from Bizarre News.