I don't want my Stepson to call me "dad"
Awe, why not?
I just don't like the idea and think it's gross.
I can understand why that would make you feel odd. It's normal if you aren't the father to not be comfortable with that.
Don't worry it was pretty easy to break him of the habit.
It is ok if it makes you uncomfortable. I think you should consider what this relationship means for your family though. It is quite an honor for someone else's child to view you as their parent.