In the episode itself, Marceline convinces Finn and Jake that her ghost friends can turn them into vampires so they can survive a trip to a "ghost dimension" to watch the movie. However, it turns out to be a played by Marceline and her ghost friends, who lead the duo through a series of "vampire" tests that are actually just dangerous stunts.
In the context of the episode " Heat Signature " (Season 2, Episode 26) , the "feature" refers to the fictional movie of the same name that Finn and Jake are trying to watch. About the Movie "Heat Signature"
It follows a submarine crew that detects a "heat signature" from an enemy, only to realize they cannot find their own signature, suggesting they might be ghosts or in a supernatural situation.
Within the show's universe, Heat Signature is a pre-war film series that Finn and Jake consider a must-watch. Key details include: