Do you agree that the Columbine High School basketball team hasn't been the same since it lost its two best shooters?
I can't believe you are joking about mass shootings.
It's just a joke about columbine, it's not like I can do anything about it.
But you can stop making jokes about people dying. If someone hears you making fun of mass shootings in school, they will be upset by it.
I don't think it's a big deal, as it will probably only annoy someone.
These jokes will trigger some and they will get angry with you. People die in shootings everyday and you never what the person you are joking with has experienced. It's appropriate to be considerate of this.