B - Safeword

Claire Cavanagh, sex educator and Babeland founder, suggests neutral words like like "yellow" for "I'm okay right now, but I'm reaching my limit" and "red" for "time to stop this"-- or choose your own, just make sure it's not something that might normally be said during a sexual encounter, even "no," or "stop," which can be confusing in some contexts, especially in bondage/S&M scenes, where the submissive partner might say "no" or "stop" and the dominant partner won't listen, because that's part of the fantasy for a submissive--giving up control.