That time I cut a huge hole in the wrong wall
I was on a job in a new build in Springfield, the kind where all the rooms look the same. The plans called for a chase to be cut in the laundry room wall for plumbing. I measured twice, marked it up, and went at it with my rotozip. About three minutes in, I realized the sound was wrong, way too hollow. I'd cut a perfect 4x2 foot rectangle into the wall of the master bedroom closet next door. My heart just sank. I had to stop, go find the foreman, and admit I messed up. We had to patch that closet wall from scratch, reframe the opening, and redo the drywall, which set us back half a day. I learned to always knock on the wall and listen before cutting, and to triple-check which side of the stud bay I'm on. Has anyone else ever cut into a completely wrong room?