I wanted to shoot up my school but, my mom said "no" Which is part of the reason why I am no longer homeschooled.
I do not understand. Are you saying you wanted to shoot up your household?
People die anyway, sooner or later. That applies to us too.
You shouldn't want to shoot anybody, much less your own mother. Making fun of school shooters in this context trivializes the suffering of victims and may create more school shooters in it's wake.
It's just an expression, fuck off.
Think of how traumatic shootings have been for the victims. There is no need to bring this up for a joke.