I did that once – wrote “heating manifold here” and drew a big arrow to the outline I’d drawn while holding said manifold against the wall. Got back that evening to find the manifold installed right over the word “here” on the wall.
I’d assume you were kidding if I hadn’t experienced similar.
When I had my bathroom fitted there was one floorboard that needed replacing.
I’d already had the broken one out, made a perfect replacement (it had a complicated cut at one end where part of the board needed to allow a pipe through), and stained the top a perfect match to the rest of the floorboards.
The plumber installed it upside down and back to front “because I hadn’t marked which side was the top”.