Oh god that moment in the Scooby episode when
Spoiler:
the Winchesters convince the Scooby Gang monsters are real. The result of this is them having a massive existential crisis. Fred feeling like he wasted years chasing masked crooks, Velma using herself as a verbal punching bag, Daphne grasping the concept of an afterlife and wondering if she's going to Hell (WTF), and Shaggy & Scooby....well, nothing. They already believed in that stuff so nothing new to them lol