Tude 

I've had that happen a couple times, scared the bejeezus outta me as I'm busy concentrating on the curb, traffic, where the cars are to me and BARK!!! WTH! Window wide open and dog leaning out - owner - not saying a word - or attention at all - hehe - until I let her know how "pleased" I was and to take care of your @#$#% dog.

solveg

You guys gotta understand that dogs alarm bark. In their point of view, a person just appeared right next to the car! Now, is this a good reason to not drive with your window open? Yes! But sometimes you have to leave it cracked because the AC isn't strong enough in the back. You're gonna* get alarm barked at. Sorry it scares you, but you have more to worry about if you hear an warning growl or a flurry of anger and the owner is dumb and has the window wide open.

Being on the roadways is tough for everyone involved, but you have to be prepared for "normal use" by everyone else.

ModoVincere

Dogs in cars barking at me don't really bother me much. Might startle me once in a while, but that's about it. I usually imagine the stupid little critter kind of giggling at me and then smiling with a big stupid grin as they go along down the road. Kind of silly, but it works for me.

What gets me is when its a person that barks at me. I've had this happen several times, and well, I just am not sure how to respond. Are they telling me they are as smart as a dog? They'd rather be a dog? This is how they communicate? I just don't get it.

Spreggy

Some folks can't compete with the world on a level playing field, so they have to get their moment of dominance by driving up to a cyclist, then speeding away. Have any of these shouters turned out to be someone you envy, like someone in a real nice car or something? My experience is they are the losers of society.

CommuterRun

It means they want to sniff your butt.

FlyingAnchor

Small sidetrack.
I was passing (slowly) a car with an old couple, they had a small yapper dog sitting walking a small circle on the ledge behind the back seat. As I was passing them I was able to watch the dog squat and take a dump in full view through the back window. I was laughing so hard by the time I passed them, then I saw them redfaced and shouting at the dog, turning their head back and forth trying to get the dog to stop taking a dump.
Steven