Once you’ve sealed the deal, there are a few things to know. Beware of shackers. Ah, shackers. The type of person you NEVER want to be, and the type of girl you always try to avoid. By definition, a “shacker” is someone who spends the night after a one-night stand, only to make the inevitable and notorious walk of shame the following morning. When you let a girl sleep over (and god forbid join her in a post-coital cuddle session), you are showing her that you care. My friend, you most certainly do not.