If you are in a simcha hall or some other professional venue, it might be problematic to scream “mouse” or “roach” or the like, because that could be harmful to the hall’s reputation.
There are other ways to change the subject of a conversation. You never inadvertently cut someone off midsentence? Spill your water (not on anyone else).
ask her to pass the salt or the pickles or ask her about her kids, husband, parents, what about those mets. anything. so you’ll look strange for a minute, so what? she won’t be embarrassed but the course of conversation will have changed.