EDIT: 75,000+ views. You people are nuts... This is how leopard slugs mate. Yes, I know that sounds disgusting, but give it a chance. You might be amazed at what you see.
Video taken from eBaum's World. Original footage from the BBC.
Note: For some reason, many people are drawn by this. Some find it disgusting and yet they watch the whole thing. If this happens to you, don't complain saying this was a waste of time because YOU are the one who watched it.