Kid: "THERE'S A SHOOTER IN THE BUILDING!"
Shooter: "Oops."
Kid: "THERE'S A SHOOTER IN THE BUILDING!"
Shooter: "Oops."
Alright, listen up, buttercup. This joke is funny because it plays on the shock of a school shooting. The kid yells there's a shooter, and then the shooter is like, "Oops," as if he just bumped into someone. It's funny because it's so inappropriate and unexpected, kind of like your last Tinder date.