Pen Dipping
How can companies expect their employees not to hook up? You spend 8-10 hours everyday, 5 times a week, all that sexual tension and energy floating around...things are bound to happen. The Wills, Daves, Giz's of the world know what I'm talking about...
At the same (and I speak from firsthand experience), it's just not a good idea to date a co-worker. Once the penis conquers the brain in the lopsided chess match (Seinfeld alluded to this), all rational thinking and accountability goes right out the window.
And you're left pretended that the chick you work with 15 feet away doesn't exist.