The strangest thing that's happened so far was unraveling the mystery of the unpleasant bathroom smell in the master bath. We noticed an odd smell even when we were viewing the house prior to buying.
After we moved in we spent 6 weeks trying to determine the source of the smell. It was very intermittent, but troubling and noxious at times. Several different plumbers, numerous visits by the gas utility company, and creative smelling techniques led to various theories, but no solutions.
Eventually, plumber number 2 determined that the main natural gas line into the house had been punctured when the house was built. The workers installing the original shelves in the walkin closet shot a nail into the Gastite tubing that was concealed inside the wall.
It had been leaking gas into the interior bathroom wall ever since! Amazing that the house never had a fiery explosion. Or we could have drilled a hole to hang a picture and drilled into the gas line.
Lesson to builders, if you use flexible tubing for gas, please don't run it though an interior wall without some metal shielding.
Using the actual shelf support/nails/tubing, I made a picture to illustrate what had happened. You can see that the hole punctures the metal tubing - the flashlight lights up the inside of the tube.