My best friend was my roommate, a few years back. I remember sleeping, and hearing a loud BANG against my door. It scared the shit out of me, I woke up, and thought I was dreaming. I was like "hello?!, what the fuck, who is there?!". Then I hear scampering off, and what sounded like the door to my bestfriend/roommates door close (our rooms are adjacent). So I get up and go to his door. I say "Dude, wtf. Was that you?", and he talks back, sounding groggy... like "w...what? I was sleeping, wtf are you talking about?". I figure I was dreaming, and slept after the adrenaline rush died.
A few days later, we're at subway, eating lunch. He says "hey man, I have to tell you something". I say "ok?". "So the time you freaked out, and thought you heard a loud bang... that was me". I say "Wtf, why'd you lie?" and he goes into the story.
"Dude I was emberassed. I was on reddit, and there was a 'NSFW' video. It was some guy being beheaded by the taliban. I had to pee, so I went to the bathroom (we share a bathroom). As I was peeing, I was replaying the NSFW beheading in my brain. As I thought about it, I got queezy, and light headed. I missed the toilet lever twice, when flushing afterwards.. I knew I was going to pass out. So I tried to get to my room, but I passed out and my head smashed into your door. As I came too, I heard you saying 'HELLO WTF, WHO IS THERE?!'. I was emberassed as fuck, after realizing what happened, so I rushed to my room and pretend to sleep. Sorry man"
We crack up every time we talk about the story.