I discovered a puddle in my washroom that led me to find a leak in the drain pipe. Looks like a plastic piece called the cam assembly that controls the pop up sink plug eroded away. I removed it and ordered a replacement, but in the meantime I have a hole in the side of the drain pipe. The only temporary solution I could think of using things I already had at home was to take the wax casing of a Babybel cheese piece, smoosh it into a ball and press it into the hole like putty. It's been working amazingly well (there's a bowl underneath as a failsafe and it's completely dry).