Usually it's my shoulder. BAM! Full force. When up in Jersey, I
   had a female friend and we'd pretend to be a married couple
   sometimes 'cause neither one of us wanted to date anybody but
   had no interest in each other either. We'd walk randomly around
   down in the evening or middle of the night, looking for a place
   to eat or find random people. She got VERY adept at throwing her
   arm out across my chest to stop me from walking across the
   street or saying, "Ken, POLE!" 'cause I'd be deep in thought in
   the times we weren't talking and... BAM. owie.