SOS!

SOS! It's a universal phrase and signal for distress, but do you know what the letters stand for?

Nothing! If you guessed Save Our Ship, Save Our Souls, or Sink Or Swim, don't feel bad, that's what most people think. but SOS started out as a Morse procedural signal. It was chosen as a distress signal because the three dots, three dashes, then three dots are easy to transmit, and not easily confused with other letters by the sender or recipient.

Once radios hit the waves in the 1920's, Mayday took over as the International Distress Signal. It's another made up word that was chosen because it's easy to remember and can be understood even if the radio signal is weak. It also resembled the French word m'adez, which means HELP ME, so it was a logical choice.

Source: William McNally, author of "Nautilus"