When you are talking with some one that your are interested friendship/dating/quickie and they casually drop the "WE" word into the conversation. This indicates that they are not available.
ME: (talking to hottie at coffee shop) So how's your vacation going?
Hottie: We (droping the WE Bomb) are having a great time. My wife and are really enjoying our selves.
ME: (hopes dashed) Oh thats great. (walking away and sulking)
