I remember one thing that happened to me last year before Christmas. I was home alone (I have two roommates but they we're visiting their family for the weekend), I was sitting watching TV feeling pretty uneasy because our house is very old and makes a lot of creepy as fuck noises. I heard a noise like tapping on my window and got really tense.... I didn't feel safe having my blinds open so I closed them then closed and locked my bedroom door as well. After a little longer of explaining away the noises in the house and trying to watch TV I needed to pee, I went to my bathroom, (I sleep in the master bedroom so I have my own bathroom) closed and locked the door behind me because if there was such thing as ghosts they're no match for 2 locked doors. I finished, washed my hands and then headed back into my room.... my bedroom door was wide open.... I remember feeling my blood run cold and thinking "this is how I die".... I ran and locked it again and tried to sleep as well as I could that night.
The mystery wasn't solved until 2 weeks later when my boyfriend was watching TV in my room with the door closed and I was in the shower. When I opened the bathroom door my bedroom door opened.... Turns out if you don't really push on my door when you the lock it the vacuum from opening my bathroom door opens the other door.
TLDR thought old house was haunted, actually just old crappy door