to insure that no one sits in your seat for five minutes if you get up (to throw out trash,
go to the bathroom, grab some chips, etc.)
it literally means that you call your seat for five minutes; if you call fives, get up, and come back ten minutes later, your seat is
liable to be taken
a very good system to avoid fights, bad feelings, and general undesirable situations
there is no such thing as 'calling tens' or any number other than five; this is because five minutes is a reasonable amount of time to
be gone for
"
I call fives, as I'm just getting a soda from downstairs. If anyone takes
my seat, I will personally kick you
in the nuts until you bleed."