A custom of you rubbing your belly and talking about how good it felt when Step-Daddy came into your room and knocked you up (lots of details) and how Step-Mom is so jealous now, but screw her, "I'm the woman of the house now" etc. and how you are going to run off with Step-Daddy and raise a family. Towards the end if you can start tweaking your nipples and talking about how your milk is coming in and you are going to feed it to step-daddy, and close with some nipple self-suck.