Roleplays typically need some sort of guidance to avoid them falling flat, such as carefully designed roleplay cards as in Short Roleplays. In this case, the guidance is a set of keywords written on the blackboard. The students are free to use these words in any way they can think of.

Each student in the group has a different set of keywords, which forces all the students to participate in the conversation. Since their partner's keywords are visible, the activity is quite cooperative: ideally, students guide the conversation so that their partner has an opportunity to use their keywords.

Before the activity, write the keywords on the blackboard. I suggest writing them in a cloud rather than a list, otherwise students might try to use them in the same order as the list, which cuts down the opportunity for creativity and spontaneity.

Explain the roles, and the rule that each person should use each keyword in their column at least once. But that's during the whole conversation—there's certainly no need to try to fit more than one keyword into the same sentence!

Afterwards, you might invite one or more groups to perform their roleplay.