Often there is too much talking in improv scenes and showing too little, this is a nice game & a nice exercise to train this:
Each player has only three sentences free for the next scene. In order to visualize this, each person receives three cards/letters/pieces of paper attached to their clothes (> just take some crepe tape). Whoever has said a sentence, takes off a piece of paper, kneels it together and throws it away.
The joke is that you can save your sentences for later (and quasi duel who has the last word), you can be wasteful with your sentences and you can already throw a sentence for a "Achoo!" (sneeze) and you can challenge the others with your sentence/definitions/tasks, but they can block less.
It's nice when less is spoken - and even more "justified": e. g."Pssst - the others are still sleeping..." (can also be communicated with gestures).