I'm not sure if you're supposed to have a "favorite traffic interaction", but a single police car slaloming for all he's got to stop 6 lanes of traffic singled-handedly is totally my favorite traffic interaction.
There's something about watching people obey police officers that are just trying to help that makes me want to do the "STAND UP" portion of "I'm Proud to Be an American".
Except I'm driving and standing up would be bad.
Anyway, from the Countdowntohomecoming archives, I give you: Police Improv
So there I am, in the commuter lane, minding my own business. Suddenly, on the far right lane, a highway patrol officer flips on his lights and his siren. He's only 2 cars ahead of me, so I'm RIGHT THERE for the action. I watch to see who he's going to pull over (and no, it was not me).
To all of our surprise, he begins slaloming back and forth across all 7 lanes of traffic. It's a weird thing to watch. At first you wonder if he's OK. It seems like some sort of automotive seizure. Then you frantically try to remember your Driver's Education days to see if they told you what this means and you remember that they only went over what to do when the lights and sirens are behind you and that slaloming was definitely NOT covered. Meanwhile, he's still slaloming and everyone's slowing down and trying to "SLOW" since that's what we think it means.
Of course, there's a couple of idiots who think that the entire freeway has spontaneously decided to drive 5 miles per hour for no good reason that start trying to whip around cars and get back up to the open space they can see. Seriously, friend in the white sports car... Think for two seconds. What are the odds that everyone - EVERYONE - would drive that speed simultaneously without reason. I know based on what you see on TV and music videos, sometimes it seems that people regularly break out into synchronized dance moves, but that doesn't really happen. Maybe you should get out more. People just aren't that organized.
I actually found myself talking to Mr. White Sports Car from inside my car. As I was yelling something like, "Pay attention! There's a policeman slaloming ahead! STAY BACK!" I realized that while I know the universal sign for choking, and I know what sign indicates "This is a McGruff house and it's safe to ask for help", I actually don't know enough signs to say "Police Slalom Ahead!!!" I really should have studied more Sign Language.
Which also makes me wonder how the police train for these types of things. I think they should have an improv class. It would be like, "OK, Officer Jenkins, you're up next. The scene is: Large debris on the freeway and you need to slow down all the lanes of traffic by yourself. Go!" and then Officer Jenkins would be like, "What's my motivation again?" and the teacher would be like, "Give me "Panic" and he'd be like, "OK. I'm ready" and then he'd start flipping on the lights and sirens and slaloming all over the place. And then everyone would clap at his brilliance except for Mr. White Sports Car who shouldn't be there anyway because this class is just for policemen.
Mr. White Sports Car really is an idiot.