Several reasons actually.
-I was going to go with "Dominous" but then I thought I'd be overusing it because I use it for many other things, so I thougt of something new..
-I went to play my Leaf-Green and remembered my charizard's nickname, which is Charmz.
-The of course I remembered my love for Lucky Charms, but using the "s" at the end seemed like...bleh.
There might of been other reasons...but I forget..
Eventually I thougt up "CharMz."
Why capitalize the "M" you might ask? Why else? It was the first letter in my name. So might as well..
Yeah...its totally unique...complete and utter pwnage.