sex in the dark, and not noticing the condition until turning on the lights or walking into a lit room after the fact. Indicates surprise of noticing the site of your passion is splattered with blood, much like a murder scene. Situation is amplified by white sheets.
Can be expanded to “Murder Mystery Dinner Theatre” to imply that oral sex took place.
Dude 2: What happened?
Dude 1: When I switched on the lights, total Murder Mystery Theatre! My white sheets were ruined!
Dude 2: Wow man, that sucks!
Dude 1: Yeah, but she did offer to clean them, so I might keep seeing her…