The farm my granddad owned has a large barn with a grambrel roof. It's a pretty big barn. My dad told me that it is big enough that they used to play full-court basketball and hold barn dances in the loft when it was empty. I'm telling you this so you get an idea the capacity so you'll understand the scope of what happened.
The barn is full of 100's of barn swallows. They use the low door that faces the parking lot out front as a place to enter/exit the barn.
The farm is now owned by an old family friend. They hold dove hunts there in the fall. One of my brothers always attends along with a large group of guys who have known each other for years.
Well a couple years back they were having one of these hunts. One of the men attending had just picked up a new pickup. He was proud of it. He parked it in front of, and perpendicular to, this aforementioned door close to the barn. It was a hot day so he rolled both windows down and, after showing off his new pickup for a while, went out to hunt for the day.
While he was gone those barn swallows do what barn swallows do so well - that is to frequent their nest via their normal entry/exit point. Since in this case there was now a truck with windows open on both sides in the path, the swallows simply flew right through the cab all day.
There's another thing that's predictable about barn swallows - that is they almost always make a dropping within 30' of of leaving their nest. Except for the owner of the new truck

it was a scene worthy of a comedy movie

as now he had 1/2" deep dropping all over the inside of his new truck and a big audience to guffaw at his bad luck.