If it s the one where Finn and Jake sneak into Ice Kings lair, it is called "The Chamber of Frozen Blades"
The episode is "Too young"
Finn takes his hat off in "To Cut A Woman's Hair" (season 2, episode 10)
Power Animal
You are thinking of the episode 'Heat Signature', in which Marceline tricks Finn and Jake into believing they are vampires.
Marceline doesn't actually bite Finn and Jake. It was just a prank. But the episode is called Heat Signature.
The episode is "Too young"
Fionna And Cake.
Finn takes his hat off in "To Cut A Woman's Hair" (season 2, episode 10)
where finn and jake practice to fight this weird gaint
Burning Low
Power Animal
Susan Strong :D
You are thinking of the episode 'Heat Signature', in which Marceline tricks Finn and Jake into believing they are vampires.
Marceline doesn't actually bite Finn and Jake. It was just a prank. But the episode is called Heat Signature.
Memories of Boom Boom Mountain
The episode with all the little people is the aptly titled season 5 episode 'All The Little People'.
If you mean the scene where baby Finn is dancing its "Memory of a Memory"