Mystery comes up with monsters/ghost/something supernatural.  
Celestia and Luna go to investigate.  
Scooby-Doo style chase scene and wacky hijinx ensue.  
Celestia and Luna come up with a plan.  
Plan goes poorly, but villains are captured.  
Said villains are revealed to be Flim and Flam.  
Brothers get arrested, get out on bail.  
Need money.  
Come up with plan to do so by scaring ponies.  
Cycle repeats again.

“And we would’ve gotten away with it, too-”  
“-If it weren’t for you meddling alicorns!”

ohhhhh