A greeting among friends mountaineering together. While climbing a straight route up the fall-line, the lead climber waits until his colleagues are distracted, and lowers his pants to expose his buttocks. While wagging his exposed posterior back and forth in a sexually suggestive manner, he calls out "Alpine HELLO!" in his best Swiss or German accent, with a flamboyant emphasis on the "hello". Bonus points are awarded if the timing is such that the next climber accidently plants his face in the expedition leader's backside.
NB: Not to be confused with the sub-alpine hello.
When we were climbing Mount Washington, I gave Tom an alpine hello that he will not soon forget!