Was Joe the same guy who went to work on the sheep farm?
It seems he observed some of the other workers getting it on with some of the sheep.
When he asked about it, they just said, "Hey...you just grab one out of the herd, put her back legs inside your rubber boots and go at it".
So....not wanting to miss out, Joe proceeds to pick out a sheep, locks her hind legs inside his boots, and has at it for a few minutes.
He notices all the other guys are killing themselves laughing.

"What's so funny?" he asks.

One of them snorts out,"You picked the ugliest one in the bunch!!