What does honking at a car on the shoulder mean?

[ForeverWinter]

We just got back from a rock climbing trip to Vedauwoo, WY from Denver. Several times on the way there and the way back, on I-25 and I-80, we pulled over onto the shoulder to take pictures. The car was safely pulled all the way onto the shoulder and away from traffic. Maybe four or five different times, passing vehicles started honking as they passed: not one long lay on the horn, but "honkhonkhonkhonkhonk" every time. Both semis and private passenger vehicles did it. They didn't slow down or do anything else unusual. By far, most of the vehicles that passed did not do it, but it definitely happened enough to be a pattern. It only happened in very rural areas, but those were the only places we pulled over.
Anyone know what this is about?

[mdmc]

1. "I see you guys!"

honk honk honk honk!

They honk to be heard; They cry out, "I no longer wish to be on the road."

[ForeverWinter]

2. Hmmm...

Maybe vehicles, too, lead lives of "quiet desperation." Or, in this case, not-so-quiet.

[ForeverWinter]

3. Anyone, anyone?

Seriously though, the curiousity is eating me. I'm thinking it could be along the lines of flashing brights at someone you want to pass, some kind or codified communication that we never got the memo about. Someone must know this...

[mdmc]

4. well... are you hot?

it might not be such a "codified" communication after all.

[ForeverWinter]

5. Yes of course I'm hot!

And humble!!

[blockhead]

6. you're not supposed to pull over on interstate highways

unless it's an emergency.

[ForeverWinter]

7. Aha!

So they were being righteous.
I sort of suspected something like that, but I hoped for better.
Thank you very much, Blockhead, for clearing that up. It was driving me (pun not intended, but it works :P ) nuts.

[blockhead]

8. and they thought you were hot...

[ForeverWinter]

9. Even better!!

[pitohui]

10. letting you know they were coming and don't step in front of them

i don't honk because honking makes ME nervous so i respect that but they are just trying to give you a heads up

[ForeverWinter]

11. That's actually really nice!

Good to know...