Humor is potentially insightful. A variety of humor is a central ingredient in some psychotherapeutic programs in which therapists exaggerate clients' problems and applaud their dysfunctional behavior. The purpose is to make clients see their behavior as paradoxical and absurd. Ridicule, sarcasm, and irony are among the principal interventions in such therapy. I think this is a typo as I believe that we should be more focused on the interviewee's response to open questions.
Interviewers use open questions to open up some new, hitherto undiscussed, aspect of the situation.
Completion probes point to neglected or inadequately covered content and call on the interviewee to elaborate and fill in omissions. Reaction probes focus on the interviewee's thinking and feeling and serve to increase emotional depth. When we make these mistakes, instead of hoping the client will not see us as incompetent, we should use the mistake as a great opportunity. To admit our mistakes is one of the most valuable gifts we ever give to a client. Interviewers can mitigate such risks by using appropriate lead-ins.