Him: Are you a school ? Her: What ?. Him: Cause i want to shoot kids inside you
I am horrified. Why are you making a joke about school shootings? Do you mean to say something else?
It was stupid joke, I don't want to kill any kids inside you!
Having sexual jokes with your partner is okay as long as she is consenting towards that joke, but making fun of school shootings and trying to normalize it by saying a joke about it is not only very problematic but also makes you unsympathetic towards the victims of school shootings. I recommend that you look up inoffensive jokes you can tell to your partner, so that your partner would feel good without worrying about the implications of such jokes.