For a MILF, dominatrix, or other form of sexually topping
woman to say in response to when a bottom sexual partner expresses that they're about to
cum.
Alternatively, a sexual joke as a response to when someone is asked to come, says they're coming (in the sfw sense), or
anything along that train of thought.
Bottom: Oh god, I think I'm coming!
Mommy: Not until I say so!
~
David:
Hey, do you know if Jake's coming over any
time soon?
Amanda: Not until I say so!