I was given the nickname Griz many (too many) years ago when I was in college at UW Oshkosh. Four of us were sharinf a house, two guys named Mike and two named John. That wasn't working so we decided to give eachother nicknames. I have always been a big guy and have had a full beard for a long long time, which earned me the name Griz. I started adding the Mr a few years back when Griz wasn't available as a screen name.
Instead of Mike, Mike, John and John we became Eagle, Fish, Buckwheat and Griz. Just to make it more interesting, me and the other Mike both started dating girls named Michelle, who we both ended up marrying.