1. Popped collars are a possible sign. Not bad; but needs some supporting evidence. Having more than one popped collar drives home the point.
2. Tattoos, especially visible when you are wearing conventional clothing. Neck tattoos lend an especially ominous appearance. And, for God's sake, teardrop tattoos, whether earned through homicides or not, are a sure turn-off.
3. T-shirts with lewd or vulgar messages. Hey, we get the point: you have a lot of undifferentiated hostility that must come out and we're targets of opportunity.
4. Calling people "dudes." Or using expressions like, "Bros before hos."
5. Penis substitute rides. Seriously, is automotive showing off really for you?
6. Wearing hats or helmets with alcohol dispensers built in.
7. Cargo pants.
8. Multi-hued golfing ensembles.
9. Having muffler cut-outs and other "notice me" features on your wheels.
10. I have a bias against guys (and ladies) who attend fall football games while being bare-chested despite thermal implausibility, and having their faces and chests painted in team spirit colors.
11. Using a cell phone in a restaurant or theatre for non-emergency purposes.
12. Having a Jersey Shore tan, whether from a tanning booth or from spray-on.
13. And having unkempt, greasy hair.
14. When parking your vehicle, occupying two or even three parking spaces.
15. But, mainly, it's attitude. That entitled, "I'm so special that the rules don't apply to me" attitude.
16. Special note: if your actions merit your being described as "acting like a male reproductive organ," then you are truly being douchy!