Bottom: Ouch, no, stop, please stop ... FISHSTICKS!
Bottom: Dammit, that's our safe word - now seriously, fishsticks!
Rob: Oh no! Stop it! Stop it! Stop it!
Jan: Ooh, you've been a naughty boy.
Rob: Please, I'm begging you!
Jan: Alright, enough for tonight you filthy boy.
Sexual safe words could also be called "sexual trust words", and they're an especially good idea in any kind of sex play that is exploratory and/or new to any participant.
Different safe words can be created and agreed upon to mean different things, such as, "stop everything, right now!", "slow down, back off!", "don't stop!", etc.
Safe words should be ones that a participant isn't likely to use as part of the play. They can be complete code, like "Tibet" (stop), "Chicago" (slow down), and "Glesga" (don't stop), or more obvious, like "red", "yellow", and "green".
No kind of sex should EVER be forced on anyone- that's called rape! (which is totally different than indulging in an agreed upon rape fetish)- and the basic idea of safe words is to prevent rape from happening accidentally.
Safe words make for hot sex!
"Yes, yes, more, more, Glesga, Glesga, please, give it to me, give it to me!" (Glesga is my favorite safe word, dontcha know, Sweetie?).
I could barely speak, but the safe word was easy to remember, so, when she went from four fingers to all five I managed to gasp, "yellow"- then a moment later I was screaming, "green! green! green!".