They're usually still laughing when the blast wave hits.
I've seen this happen so many times in my life I can't tell you.
It's the people who will snicker at you the hardest who will pound on the hatch door with the worst desperation begging to come in.
I've seen it happen during tornados, civil unrest, fires, floods and power outages. Those who considered the future the least will always be the most terrified when it gets here. They just never believed that whatever it was would actually happen and felt it was fantasy to even suggest it could. They honestly think that reality is some kind of climate controlled Disneyland ride where things only appear to be potentially dangerous - the authorities will see to it nothing could actually harm them. They believe that somebody in government sets safe operating parameter guidelines for the quantum universe with central legislation. Don't laugh. It's true.