I've got a few.
My Wards name is George, he's heavy as a brick
My White's name is Betty. Every time I move her I have to tinker with her to work again. So she was named "bit**ing Betty"
My Domestic is named "Iron Side" because I swear she is made from Cast Iron.
My Surger is called "Nippy" because she has nipped my fingers more than once.
My new Singer is called "Baby".