feet seats
The seats that are in front of you at an event on which you place your feet in hopes no one will sit there.
Ex: I really hope no one sits in front of us, those are our feet seats!
move your feet lose your seat
A true and ancient custom among people with access to less chairs than people in need of a seat.
For example Peter goes to the loo and Carlotta steals his seat - when he returns she says "move your feet lose your seat' and Peter can no longer argue.