Duck and Cover
The rationale behind "duck and cover" as a protection strategy in the event of a nuclear assault always seemed a bit fishy to me. After all, if an atomic bomb lands close enough, the fragile human body is likely to transform into a black smudge on the ground, no matter what position you're in.
But the tactic actually did have a practical purpose (assuming the bomb didn't get dropped right on top of your home, place of business or school): if you're ducking on the ground, you're less likely to be caught looking up at the source of the explosion, shredded by flying glass from the shockwave. Apparently, "duck and cover" is still used in US states plagued by tornadoes and earthquakes. Good to know.