Reed College term coined to impress upon freshmen the fact of life that sleeping with your dorm mates is a bad thing due to fun and enjoyment of meeting your one night stand partner in the bathroom every morning for the rest of the year. Term varies by colleges (example: floorcest) and is well understood by most, if not necessarily followed. Alcohol might play a part in this. Many long-lasting and happy successful relationships have come from ignoring the implied advice of this term; so have innumerable black pits of despair. It's your choice.