Two Line Vocabulary is a little weird for a couple of reasons. It’s a fundamentally simple game, particularly because the scene is generally only about two minutes long. This is a scene game for three people, and it functions much the same way as Actor’s Worst Nightmare. This is often low energy because the humor derives from the things that are said, but sometimes the actions can be funny, too.
The way it works is that one person, the main character or “anchor” of a scene, has to justify everything that is being said by the other two people in the scene. The only caveat is that the other two people in the scene can only say two phrases each. For example, one person might only be able to say “Don’t touch that!” and “I love you.” and the other person can only say “Where are we?” and “Not again!”. Since the third person can say whatever they want, they have to make each of those expressions make sense given the context every time it is said. So, once you get a suggestion (typically of a location, but anything works) you go on your way and establish CROW just like any other time you would play a scene game.
As with every game, there are a few things actors should keep in mind as they play. The first is that for this game in particular, there are no stage entrances or exits. All three actors are on stage the entire time it is being played. This can be difficult, as it means nobody can come in to save you, but since everything should be tied around the anchor who can do whatever they want, this shouldn’t be a big problem.
The second thing is that the anchor is always the focus in this game. Since the other two improvisers are so limited in their dialogue, it’ll be impossible for there to be any meaningful interaction between the two. This means that the anchor should be talking roughly half the time, as after either of the other two says something, the anchor should be replying to it. (The anchor doesn’t have to reply to everything that is said. If the natural flow of the conversation doesn’t call for a response, it isn’t necessary.)
While it’s the primary job for the anchor to justify anything the other two say, it’s also important for them to carry the scene forward. Make sure all three people are dealing with (but not solving) the conflict as the game progresses. This can be the hardest thing for new improvisers to achieve, so when in doubt, move the scene to a new location. It’s also important for the anchor to not ask questions as, outside of silent gestures, each of the improvisers can only respond in two ways. So as long as the anchor carries the scene justifies statements without denying or asking questions, this game is a cinch.
Here’s a link to WLIIA performing this game a few years back.