Let's see if I can remember all of mine over the years.
My '76 Mercury Capri was "the Indy car" because the metallic green paint stood out like a neon dick, ND.
My '85 Dodge Shelby Charger Turbo was "Myrtle" for reasons that escape me now.
I had a Pontiac Catalina for a while that I called "PBY" after the WWII seaplane.
There are several stories behind the Chickenhawk's name that I won't go into again.
"George," "Gil," "Marty," "the Chuck wagon," and "Johnny Turbo" were all named after the people I bough them from.
"The Louisiana Purchase" was purchased in Louisiana, duh. {Edit} I suppose some folks from other countries might not know what the Louisiana Purchase is, now that I think about it. You see, a vast stretch of the central US, starting in the south in what is now the State of Louisiana, was bought from the French sometime in the past, I don't remember when. That was the LP. US history lesson over. {Edit}
"Herman" was going to be the monster truck, is ugly and green, and therefore named after Herman Munster from the '60s tv show.
"Mini-Pearl" was going to be a miniature version of Mom's Maxima which she calls "Pearl."
"Gilligan" was a play on words after "Gil" became "Mini-Pearl" and then became "Gil" again.
"The Fauxbra" is a faux Cobra.
I was told that Matador means Killer in Spanish so the AMC Matador is called "Killer."
There's a "Honduh" out back of the shop that we all try to claim belongs to one of the other guys.
"Johnny Turbo" became "Super Karate-Monkey Death-Car" for a while until John bought it back. I think it was to save it from that name.
Well, that's all I can think of at the moment.