According to my brother I was almost white as a sheet after shutting the basement door. Being the teenage half-wits we were we called some of our friends who had an interest in ghosts and such. 5 of us headed downstairs with all the lights on, everything is normal as it can be. The only thing of note I saw was a lone ping pong ball in one of the corners. So we get the bright idea to shut the lights off, get the cat out of the basement, setup on the couch we had down there, and kill the lights. It's quiet for a bit, we start bullshitting as teenagers do. The bullshit's cut short by the sound of a ping pong ball bouncing. A couple of us freak out, we start going upstairs, someone gets the idea to do something. Dude puts a leftover 1x1 piece on a wall opposite of the stairs, then we go up.
At this point parents are wondering the fuck's going on with the sound of 5 dumbasses running up the stairs. Mom thinks it's funny, Dad wants to go check shit out. Dad goes down with the lights on and the first thing he asks is "who put this board in front of the steps?". The 1x1 was now leaned across the front of the steps. From that point on even after the basement was finished I always had some feeling of being watched. None of us wanted the bedroom down there anymore. Years later I asked my brother if he ever saw or heard anything while down there. Said he saw what could be described as a living shadow, and it vanished as quick as it showed up. He said after seeing it there was this unspoken rule in the house that no one goes in the basement room closet.
Parents moved out a decade later. Another family lives there now. I wonder if they have any weird shit happening in the basement.