This paper argues that 'radicalising' the classroom means more than merely teaching radical content; it means transforming the formal aspects of the classroom encounter - by abandoning practices that train students in attitudes and behaviours consistent with current hegemonies in favour of practices that foster the habits and skills of critical citizenship rather than the habits of consumer capitalism. Drawing on the democratic tradition of radical educator Paulo Freire and the theoretical work of Henry Giroux, this paper examines one classroom encounter to show how simple classroom advocacy can reproduce dominant social relations that undermine its own radical content. The paper concludes that instead of mere advocacy, realising the radical potential of teaching requires practices that transform the classroom into what Giroux calls a 'vital public space.'