Pro tip: Always manually check for pipes before cutting into a wall
I was patching a hole in my bathroom drywall. My stud finder gave a clear signal, so I went ahead with the cut. Ended up slicing right through a copper water line. Now I'm dealing with a flooded floor and a plumber bill. Take this with a grain of salt, but in my experience, knocking on the wall or using a magnet can save you big trouble.