Deal everyone a hand just as in 7-card stud and one more hand known as the Ghost hand and set it aside.
When there is a showdown all players turn their cards over including the ghost hand.
The player to beat his opponents hands and the ghost hand takes down the pot, if the ghost hand cannot be beat in a showdown then the pot remains and another hand ensues.
As long as the ghost hand keeps winning against other players hands in a showdown then the pot just stays until the ghost hand gets beat or all players fold before a showdown.
If there is no showdown then the ghost hand is not revealed and the last player to bet/raise takes it down.
Variation: You can use a ghost hand in Hold'em as well.