This is mildly funny in a creepy sort of way, but it works very well for Halloween. YouTuber MrKreepyKoala decided to dress up like a serial killer and silently hunt and kill Grand Theft auto Online players. Here's the description of a short video he created called "Creepy Murderer on GTA V!"
"In this video I went into lobbies on GTA around 3 AM and started playing creepy lullaby's sung by women and children. I then went into passive mode with my radar turned off so they thought I was invincible and unaware of me being in passive mode!"