That the most manly thing you can do is be intimidating. Big muscles, big car, loud car or bike, acting angry or tough. None of these things make you more of a man, in fact offten than not they make you look insecure and less of a man.
I think the most manly thing I do is wear pink, I recently got a custom make shirt,bright pink with a big honkin "I love cowboys" printed on the front. Teenage me would be cringing but my thought is, "if you're manly, you can handle the color pink"