Honk again...

How often do you use your car horn?
I, for one reason or another, don't use that wonderful object of "frustration identification" quite enough.

A few weeks ago we loaded up the family for a trip south so we could eat out.
(After all, the only way to celebrate Mother's Day is to eat at The Outback.)
As we waited in line we found ourselves next to one our youth leaders (who is incidentally from the USA and was headed home from church).

So we rolled down the window and had a nice little chat to kill time as we waited.
Since the line we were in wasn't going anywhere that quickly we let a space develop between us and the car that was directly in front of us.
Keep in mind that the vehicle in front of us was still about 3 or 4 car lengths from even entering the border crossing.

Then it happened...HONK!
What?!?! You've got to be kidding me!
The person behind me had the nerve to honk, as if I was preventing them from getting to their destination.
Ok, I have a hard enough time understanding the "quick honkers" who lay on the horn if someone sits idle at a green light for more than 2 nanoseconds, but this was utterly ridiculous!

I'm not holding anyone up.
I'm not preventing anyone from getting to their destination.
I'm just passing the time by talking to someone in line next to me.
Please be advised that you will not get there sooner if I pull up 10 feet.

Do you have guidelines for when and where you use the horn?