My two favorite arm pump stories:

First one, I was cruising along some highway in rural Missouri, carrying some farm equipment up to Iowa. There were a lot of Amish folk out that day, and so I was dodging their buggies every couple of miles. Coming up on one buggie, just as I'm about to pass I notice a couple of little Amlets in the back doing the arm pump. I didn't want to spook the horse, so it was just a little baby toot, but that absolutely made my day.

Second story was somewhere in Tennessee or maybe North Carolina, I forget exactly. Either way there was a nasty traffic jam, and I heard over the CB that there was a detour along a surface highway to get around it, so I followed the other guys off the interstate and through whatever town we were in. As it happened, that little convoy passed right by an elementary school, and the whole place was out lined up by the fence doing the arm pump. Let me tell you, I have never felt more like a king of the road than when I laid on that horn for those little buggers.