Whatever your pleasure, to keep his game on track by accepting the
terms of the game is doing what to whom and for how long. Anne Hooper,
in his delightful little book of casual sex, suggesting an agreement
on a code word for games of domination, a kind of mercy that the
message definitely means "stop now." This avoids confusion between
"no" (do not you dare stop doing) and "no" (I wish I had never seen
that pink tutu).
http://www.sexgamesreport.com