'Cit,' '4F,' or Jimmy might do very nicely. I especially like "Jimmy;" this might simply be because a couple of Brooklynites I went to college with liked to say "Oh, Jimmy! Oh, Jimmy! Oh, Jones!" when they were excited -- not to say that's especially witty, just that, for me, there's a bit of nostalgia tied up with it it. 'Jimmy' would need setting up, which is doable. As to 'being at all well known' being relative, Mr. Musick, it needs to be known well enough for most people to follow. ;)