One person is allowed to SIT on stage, one person STANDS etc. The scene gets interesting when there are a lot of switches and if at least at one point everyone is on stage. Make sure the switches are logical in the story. Make the stances very clear so that the audience can see well who has which stance.
N.B. Even if you move you do this in one of the basic stances.
Variation 1: The sunglasses game – Each player has a pair of sunglasses and instead of sitting standing lying squatting you come up with four ways to wear the sunglasses. Fun outside in the summer, do make sure you explain it to the audience well and that it doesn’t devolve into a mess(…).