In this article, the author offers a sociolinguistic discourse analysis of two conversations in which a preservice teacher encouraged her urban, 10th-grade students to disagree. The author's analysis demonstrates the positive effects of the teacher's use of indirect challenges and provocative paraphrases -- features of the African American sociable conflict-talk practice known as The Dozens -- to promote collaborative disagreement during whole-class discussion. The author argues that teachers can promote collaborative disagreement in whole-class discussions by appealing to students' home-cultural disagreement practices, which may already overlap with argumentation practices valued in school settings. The author calls for further research into the influence of teachers' and students' out-of-school discourses on discussions characterized by collaborative disagreement -- a practice that is essential to ELA curricula and to participation in a democratic, literate society.