A young man was planning to get married, and asked his doctor how he could tell if his bride is a virgin.
The doctor says, "Well you need three things. A can of red paint, a can of blue paint and a shovel."
The man was astonished and said, "What do I do with those?
The doctor replied, "Before the wedding night, you paint your one ball red, and the other ball blue, and if she says, "that's the strangest pair of balls I have ever seen," you hit her head with the shovel."