I started on a Bbb tuba named "Heinrich" after Heinrich Hermuth from Gelsenkirchen, Germany, who had built it maybe 50 years ago. Later I purchased a MW 46, which was named "Chantal", because that reflected the quality of my relationship to the two horns. One was the reliable buddy to hang out and have fun with, and the other... aahm...
I now own a PT20. She definitely is female, but hasn´t given me her name yet, although we´re dating a whole lot and Chantal is getting jealous , Heh heh...
One man in band named his old, battered kaisertuba "Bertha" after "die dicke Bertha", a giant train-mounted cannon made by Krupp. He sure tried to play up to that concept.