What is so funny?

I could post about 20 photos from my recent weekend with the fella's but due to possible repercussions I have opted for a few "classier" ones. On this one you have to wonder what DH was laughing at on the golf course? Is it a photo of himself? Is it pornographic by nature? Does it involve livestock?

However I cannot divulge the true subject of this photo but it will always be a precious and lasting memory to me.