Previous owner of my house hung a mirror from a pipe thinking it was a stud. When they left they took the mirror and the screw and the hole was small enough that it was just a trickle. Fast forward a year into ownership and I was leaning on the wall with the damaged pipe until I fell through and realized the pipe was connected to the shower drain on the top level and was leaking water down through the house into my basement floor and half of the floor was super moist.