The TTT Thriller SWEP is similar to a Dart Gun. The traitor may buy this weapon only once per round. The Thriller has 2 shots so you better not miss. TTT - Thriller example: https://www.youtube.com/watch?time_continue=2&v=zoIC45y3RSs
Yeah I'm going to have to agree with @Spookturnity on this, as much as I think it'd be a funny Halloween-themed weapon I don't think it would work really well before or after the month of October. Sorry.