Me and Hubby never used safe word, but thats because we have an instinctive way of communicating with one another. We never needed a safe word to talk/communicate, but thats because when we started "playing" we already knew each other thoroughly and were so committed to our relationship, I felt safe with Him. He is always most cautions of my stress levels, and if we are going to be introducing something new - we talk about it, a lot and He often leads me through step by step, it helps Him catalog my responses and establish parameters of how much I can take for future references.

But to play without safe word with someone with whom you have no such guidelines is not sane. In fact, even if I planned to not ask for a safe word to be given to me in the first place, but a Dom/me told me I am not being given one/am forbidden to use it - it would be a deal breaker and a sign that I cant trust them to take care of me/my safety.