1. Cyclists who ride against traffic
As a kid, I remember occasionally being told that it's safer for pedestrians to walk toward oncoming traffic, apparently so you're more aware of potential danger. (I don't ever remember saving my hide by leaping out of the way of a speeding motorized missile at the very last second...)
If it's so (and it's probably more perception than reality), the notion does not carry over to cycling, where you're further out into traffic. Besides defying statutory law, it defies the laws of both physics and common sense. And it REALLY annoys people who are using the road correctly.
(Amazingly, my wife insists that the first time she took the driver's written test - as a 16-year-old in California - she got scolded by the guy administering the test, when she answered that bicyclists should travel in the same direction as traffic. Incredible!)
2. People with earphones jammed in, when they need their senses
I see cyclists (and motorists) in heavy traffic situations, who are blunting their sense of hearing. I constantly happen across iPod-disabled people on bike/pedestrian paths who are startled when I come up on 'em, and act like it's my fault they were oblivious to my approach.
It isn't right, but women in particular should be acutely aware of their surroundings when they're alone in a place like the Greenbelt. An assailant could sneak right up on 'em when they're jammin' to the head tunes.
(I love the MP3s as much as the next guy... but there's a time and place. I'm gleeful about my new toy - a Cowon D2 player. Check it out on the web.)
3. Motorists who act like it's no big deal that their cellphone is severely impairing their driving ability.
Let me put it this way... if your driving-while-yakking is so bad that you would never pass a driving test, put the #*&$@ phone away! And there is a huge percentage of drivers these days who fall into that category. (Do you know it's illegal to turn or change lanes without signaling? Or are you just ignoring that particular law, so you can jabber?)
4. Adults who take up smoking
I guess I can understand (a little bit) why a dumb-punk teenager would take up smoking. (It never tempted me, even as a kid, but it's so grown-up and rebellious, and all that.)
I know a few people who have taken it up as adults. (Are they just feeling too darn healthy? Do they pity those poor tobacco-company executives? Is it so they, too, can stand outside in a blizzard, shiverin' and puffin', and bask in the glory of the experience?)
5. Single Welfare Women who already have 5 kids under the age of 7, but just the same get fertility treatments and have 8 more young'uns.
Humans are spoze to be smarter than rats and bunnies... but some apparently aren't.