You can model this by first reviewing ten vocabulary words the way you and the class likes best. Then, using the entire class as your partner, compose and write a dialogue on the board.
Humorous dialogues are more effective than others.
Pair students, let them do the same. Have the new pair practice the dialogue, making any changes to correct grammar or improve the dialogue. The teacher does not grade, review, or correct. The exercise can be introduced in one class period. Once established, however, you can use it once a week.