A hiroshima
When you're jacking off and you call your mom to your room. Then you hide behind the door and she walks in and you cover her face with your junk.
My brother jacked off while my mom walked in, and it was a full-blown Hiroshima.
When I jacked off and my mom walked in, it was like a nuclear bomb went off.
My mom walked in while I was jacking off, and it was the worst Hiroshima ever.