If they had the best cake or type of cake that I wanted for my child's party or any party for that matter, I would buy it and not worry about the name. I would also explain it to my daughter if she asked. One of my friends back east used to make erotic cakes because she could sell a cake that takes the same amount of time that her princess cakes used to take for about ten times the amount. She made my daughter's Winnie the Pooh cake for her 1st birthday.
I don't remember how old your children are but if they are in school, kids talk about all kinds of stuff. My daughter is in middle school and most of the kids watch Game of Thrones. I won't let her watch but if she asks me a direct questions about something she heard about the show, I will answer. I would let her watch if it wasn't so violent.
My daughter is now 12 and I've always answered her questions and not "sheltered" her from the world the she is going to be on her own in, in what for me is a rather short time. She asked my husband and I about "69" the other day because some kids were referencing it at school and she didn't know what it meant. I explained. My husband froze. He said later that he thought I was brilliant, which is always nice to hear from your partner.