So my best story happened not to long ago.
I had invited two other people over for a small trade and they wanted to see one of the rooms I had just fixed up so I said yes. Someone came in the town but I had no clue who it was and I missed the screen where he walked in. I just told him we were in the house in the backroom. This guy walked in and said "HEEEEEERE'S JOHNNY!!!". Dressed up in a hockey mask, custom shirt with a blood spattered pattern and an axe.
He proceeded to chaise us around the room wacking us with the axe. I didn't end the session because I thought it was hilarious and that the other people must be in on it. This went on for awhile and I only ended after everyone ran out of the house because I didn't want my flowers trampled.
None of us knew the guy and I never found out who it was Johnny hasn't come back since.