The implications of safewords..

[Ozme52]

I agree with Ozme52, only one word is needed. However just not the word "mercy" since that can be used as part of a scene.

Well, any word can be used as part of a scene... Mercy works because it just isn't part of our daily vocabulary.
Most of the other words people "tend" to suggest are far more common. Even Family Guy's "Banana" is more likely to come up in our conversations.

No one has ever said to me "Is that a Mercy in your pocket or are you just happy to see me?"