The stupid thing about this situation is it's a HUGE LEAP to assume why she was even accidentally calling out her moms name. In any other situation, I would assume she's nervously calling out her mom's name like a young person might do in a particularly tense situation seeking some kind of help, instead of actually thinking of doing dirty things with her mom.
Shhhh. She's a fast learner, she learnt this was a manga and what its plot is.
*hands you "most-witty-comment-of-the-hour-award"
But, srsly, she could have started out to say "No, wait, Mom told me two girls can stil get pregnant and have gay babies, so we maybe should decide on names first" or whatever.