"put your head between your legs and kiss your a** good bye"

Did anyone ever hear the phrase
"put your head between your legs and kiss your a** good bye"

we were talking about if we go to war with Iraq and someone said this if anyone know how it started or where it came from I would appreciate it!

It probably came from the Civil Defense drills we had to do in U.S. schools in the 1950s/60s.