Scary signs in minecraft?

Ok so me and my friends have been playing Minecraft on my ps3 and we went up to his room on survival. And we found something a little scary, a wooden sign that just had a number 8 on it. The next night we found the # 7 in our house and then 6 and all the way to 1. We were a little scared and then this really scared us, in our kitchen we found a sign that said "night" on it. We knew none of us were doing this and so we got off. Now i'm not an expert on Minecraft and I just want to know what's going on. Please tell me before I get back on and something goes wrong.

Lol what

I don't know why MC is so popular looks quite boring to me

I don't play MC much/all so I really can't help you. But assuming none of you are doing this to the house. W t F?

HEROBRINE ISN'T REAL

Your friend must be doing this there's no other answer hero brine was a made up character to scare people the only real explanation is your friend is doing or someone else go onto your PS3