Guy in Bakersfield asked me to run his cable 'somewhere the wife won't see it' and I still think about it
He walked me around his whole house pointing at random spots behind furniture while his wife was at Bible study, and when I asked what the TV would sit on he just said 'I'll figure that out later,' which is how I ended up drilling into a wall that had a water line exactly 2 inches behind it.
Next time put your hand on the drywall first and feel for cold spots before you cut. Water lines run horizontal through the middle of the stud bay more often than people think, usually right around outlet height. Also worth asking where the cable box and power are going before you start, because I'll figure it out later turns into a second trip every time.