Third Person Walking Rule (poker)
In a public card room, once two people have gotten up from
a game (and left their chips, so that they remain part of the
game) for whatever reason, the next person to get up is given
a button by the house dealer and informed that he must return
before his next blind or he will be picked up. This rule helps
to keep games full, keeps them from breaking up, and yet still
allows the third player time enough to make a quick restroom
trip or take a smoke break.