This event occurred about 2 years ago. I was at a friend's party and his basement is haunted or at the time so he claimed it to be because, allegedly while the house was being worked on one of the workers had died. Here is how we proved that his house really was haunted. I was with my entire group of friends, we were all a bunch of scaredy cats but we all loved the idea of the paranormal, and I am still a huge fan of the paranormal.
All 5 of us are down there for a few seconds and nothing happens, so we all head back upstairs then I get the idea of we should all go down there but in groups so the first set goes as a group of 2, they hear a loud crash and so we all go down there to see what happened. We find that a mirror had broken on the other side of the basement, when there was absolutely nothing around it and it was laying flat on the floor.
Then the next group goes: Me and two of my other friends make our way down the stairs while the other two stay upstairs two floors above us, one of my friends had brought a baseball with him to try and freak my other friend out. So we get to a few steps before the basement floor and my friend throws the ball far into the room -thunk- the other friend freaks out. Well not seconds later in that same room -thunk- we all got the hell out of there and we go tell our friends what happened, a few moments later we all go downstairs into the basement with the lights on to find the exact same baseball sitting at the bottom of the stairs. It's safe to say nobody went back downstairs for the rest of the night.