When I was extremely young I was called Pumpkin because I was a chubby baby. My father used to call me Scabs as I was always injured and had cuts and scrapes and stitches ... and nothing has changed. A friend who I joined TKD with (who quit at white belt) called me and still does Band-Aid Boy (same reason). During my junior/high school football days I was called CO as I was usually a captain and also because something to do with my last name and it always being mis-spelled. My wife likes to call be Darebear.
When I first joined TKD we did some grappling but not to as much as we do now. We had brought in a Roman Greco coach and I manhandled quite a few people and my Instructor nicknamed me The Bull at that time. All in fun.