I name mine generally from the name of the previous owner, if it works. My 3930 is "Ronnie" after the gentleman farmer friend I purchased him from; the model 1920 is "Frankie" after the man I bought him from. My 1944 9N was my father-in-law George's - he acquired the name "George" long before I owned him because his key-fob said "George" so that the half-dozen or so neighbors who used him frequently would know the right key.
My L2850 SHOULD have been "Kurt the Kubota" after the guy I bought him from, but that man turned out to be such an a@&%#*& by the time we closed the deal that THAT was ruled out, so he's "Knipper" after a particularly difficult biting Walking horse stud that was an ugly, gnarly beast from too many times ramming his head through barbed wire (some previous owner obviously rolled the tractor with a heavy high bucket; many ugly weld repairs to FEL arms and front end).
I name everything: Grizz, the rAT, Linda (the Blue Bayou), Mickey, Ned. The wife named her Gator Cubby. All part of 'the family'.