seatscams 

'no seatscams' is something said at parties or other gatherings where there are fewer chairs than people. When someone gets up from their chair, if they call 'no seatscams' then anyone who takes their seat must give it back when the former chair's occupant comes back. Witnesses are typically needed and enthusiastic to enforce the rule.

'Don't sit there, Rick called seatscams before he went to the bathroom'

seatscams by Melted-Ozark December 15, 2011

seatscam 

When you have to get up from your chair to do something, and someone steals your seat. You can save yourself from a seatscam if, before you leave, you call "no seatscams".

Ted tried to take Gary's seat, but unfortunately Gary had called "no seatscams", so he had to surrender the seat to its original owner.

seatscam by Krakko January 11, 2008