This is a chimney elbow, aka chimney pipe, commonly used for well, chimneys and stove pipes exhaust.
Then, there are bus exhaust pipes. Nary the two shall meet. Or so you thought.
This gem combines the two in a way you may have never thought possible. Or thought smart.
But it was functional and held, at least for the few minutes we drove nearby on a highway at high speeds.
This was captured in the Czech Republic. Turns out, people in other countries DIY it crappier but cheaper, too.