Another (more
genteel) way of saying "
Put your head between your legs and kiss your sweet ass goodbye." A "
civil defence" measure used to provide some measure of
protection during an
earthquake or a nuclear attack. I'm not kidding about that,
BTW. See the
Cold War documentary "
Atomic Cafe" for a
cute little cartoon turtle advising
school children:
"So when you see the H-Bomb flash, DUCK and COVER!"