Cars or Religions. The best use of a car metaphor in my view, was in Neal Stephenson's classic essay, "In the Beginning Was the Command Line" (wiki, Neal). And then there was the classic "If operating systems drove your car..." (which is getting hard to find, but not impossible).
I know. I know. It's all brain noise. But it amused me, even where I disagreed with the way he described his categories. For the record, I use C, C++ and python I've begun to play around a bit with erlang. I'm beginning to be surrounded by C#-of-borg minions but I was just as amused to see no entry in either list for Objective-C. Let me see if I can come up with one.
Objective-C as a religion would be whatever is believed by children of a couple where one is from a Jewish and the other from a Christian background. Neither is very religious, and only periodically remember that, "oh yeah. It's Passover. I was going to stay away from the ham for Passover."
Objective-C as a car would be like a Fiero. Nice sporty exterior and sometimes it can run really, really fast. It's not so great on the corners, though and if you park it in one place for too long, there are oil stains on the ground.