I got into cannon through friends that do renaissance faires, and they have a rule that you name your weapon the first time it draws it's owner's blood (most of the time it's a sword, dagger, halberd, or other type of "sharp" weapon). Though I don't follow that rule, and generally don't try to name my inanimate objects, I did once try to start calling my car "Black Stallion", but it just didn't stick.
My largest cannon, however, does have a name. It's a 5/8 scale (1.5" bore) Hern Carronade that got it's name from my friends, rather than myself, though. I built my carriage (and my cannon's sister's carriage) out of a single board of 8/4x14"x13' red oak, and I decided to try using old world processes to finish it. In doing so, I made my own acid stain, which, when applied to the red oak, turned it purple. After finishing it with linseed oil, there is little trace of the purple, but in telling that story to several different friends, they each told me that the first image that came into their heads at the thought of a bright purple carriage was Barney, the dinosaur, and the Barney name stuck.
My friend, who's wife bought Barney's sister for him as a Christmas present, chose to finish his carriage with a minwax stain, so it never had the purple color, but he fabricated a tompion and a strap for it and for the vent cover out of leather, which earned his cannon it's S&M name.