A rather simple exercise in improvisation. Two players step on the stage and start acting out a scene. A player who blocks any offers is switched out for an actor in the audience.
Example:
X asks Y to give him massage. Y asks, is a head massage ok? X affirms that it is. Y starts rubbing X's head. X ask Y to move to lower parts. Y rubs X's shoulders. X demands Y to proceed even lower. Y is desparate to get out of the situation (Y isn't used to getting laughed at), so Y shouts: "Isn't that your wife over there?" The "referee" of the match stands in and Y has to move aside. Now Z steps in and starts rubbing X's stomach. Z asks X to move closer, because it "feels good"...
At some point it might be a good idea to stop this exercise.
This exercise is great for beginners of improv, because you really have to accept the offers of other actors. Without accepting, a scene does not move!