It is probably to demean the men who own them.
I guess that, for some men, they are. Or they like to think so, anyway. There are also other ways that they might compensate or demonstrate their masculinity...like "power trucks" or power tools. lol<br />
I think it goes back to the way so many have chronic sex on the brain. <br />
I had a professor once who saw sexual metaphors EVERYWHERE. What a loony lady.
You hear it a bit studying film too. Definitely changes the way you watch action movies lolol