If you engage any in level of kinkiery it’s highly advisable that you have some sort of safe word or means of communicating if you need things to slow down, change, or stop altogether. While words like “no”, “that hurts”, or other similar words and phrases could be used – most people find that when involved in most BDSM practices that people are going to say words like “OUCH!” or “FUCK THAT HURT” – but that doesn’t mean they want or need it to stop. They probably are experiencing some level of pain, but desire for it to continue.
You need to have some means of communicating that you just need the event to slow down, but still desire to continue as well as a way of saying stop the press right now. Many people use a color system – Red/Orange(or Yellow)/Green. But it’s also important to have a way of communicating if the submissive is gagged. Whatever is needed for the scenario, just tell your sub how you want them to communicate.
And, if she starts screaming “ELEPHANT, BANANA, SENATOR, BLANKET” odds are, she forgot her safeword, lol