A phrase used to reduce the awkwardness when you get left with a person you dont really know (eg when alot of people go to the toilet or bar)
*catie, jayne, chris, aaron, mary and tom ALL go to the bog
, leaving you and the pretty girl you dont know yet*
*you* "hmmm, and then there were two.......
best used BEFORE the awkward silence to show your not at all bothered by the scenario