Drawing on task-based conversations in Korean and Japanese, this paper discusses three examples of self-deprecation: the use of self-oriented negative interrogatives demonstrating insecurity or self-doubt; self-deprecating elaborations uncovering one's frailties or personal issues; and the collaborative character of self-deprecation. Self-deprecating language, in which speakers degrade or humiliate themselves toward their addressees, does not add to communicative efficiency under Western culture-based frameworks. But it is claimed in this paper that, at least in some cultures, self-defeating language is a significant device used by interlocutors to level with each other and become of ‘one mind’.