In fact, it's an ancient rune (written twice here) wich is the pendant of the letter "s" in the rune alphabet and it symbolizes the word "sun" as well. The Nazis used it in their obscure obsession with nordic myths as symbol for their "Schutzstaffel" (as mentioned before) and for the youth organization "Hitlerjugend". The Schutzstaffel used the double symbol, the Hitlerjugend just had one "S". But the Nazis didn't use it for it's meaning of sun but for it's meaning of triumph. (That meaning came from an völkisch mystic named Guido von List who made up a new rune alphabet with know symbols but made up meanings. He called the "sunrune" "triumphrune", in german "Siegrune".
For the one's who like to know some useless history stuff. The others may just vote down.
(I laughed hard at your lufthansa comment. Good one.)
replydetachattach picture