Mine came from the fact that I love heavy, moshy metal....and while at a basement show, somewhere in Buffalo (can't even remember who was playing now) I was in the middle of the pit, throwing up windmill punches like it was my job. The band that was playing broke down in to this mosh in the middle of one of their songs that sounded like the one at the end of SOD's Toxicity and screamed "Piratemosh"!!! at the top of my lungs. It was all over after that. I never heard the end of it and that was over ten years ago.
I use it on Every. Single. Forum. that I'm on now.