Finn's Fantastic Voyage is an episode of Adventure Time where Jake goes into Finn's body to retrieve his spaghetti, of which Finn ate believing it was his.
[Jake makes a plate of spaghetti and sets on a table and goes to use the bathroom and Finn comes out from the bedroom and sees the plate.]
Finn: Oh plate, there's no hate, I just want, that spaghetti.
[Finn eats and Jake catches him.]
Jake: My spaghetti! Finn did you eat it?
Jake: BMO is a witness!
Finn: Um, we took BMO to soccer practice.
Jake:Did you eat it?!!
Finn: Alright, yes.
Jake: Dude, I spent forever cooking that!
Finn: I didn't digest it! Maybe PB has something that can help!
[The screen cuts to an outside view of the Candy Palace and then inside showing Finn, Jake, Marceline, and Princess Bubblegum.]
Finn: So do you have anything that can help us?
Bubblegum: I could get you to go into your own body. Perhaps we should try that?
Finn: That sounds like a bononza idea!
Jake: Wait Finn, maybe I can just make another plate of spa-get-me.
Finn: Come on dude it'll take a few minutes, we still have time to get it!
Bubblegum: This serum I made will put us inside your body.
Marceline: So will it like turn Finn inside-out and we go inside of him?
Bubblegum: No, our artificial inteligience will transport into smaller versions of us and will go into Finn. The only problem is we don't have small versions of us.
Finn: Hmmmm. WAIT!
[Finn pulls out the bag with small people from All The Little People]
Finn: These peeps might help us.
[Scene then cuts to Finn sitting in a chair and the others passed out also in chairs. Finn, still holding the bag looking nervous and sweating.]
Finn: This is probably how Simon felt when turning into the ice wad. I should look outside for happy things!
[Finn looks out the window seeing Flame Princess watch Lumpy Spac Princess chug down a can of beans.]
Flame: I don't think that's a good idea.
LSP: I'll do what I lumping want!
[Finn then closes the window and hatches a new idea.]
Finn: I'll sing a song!
Okay, now my friends are tiny and inside of me
I'm also strapped to chair which is really bad
It is because I have to pee
Yeah, now my friends are as small as Gumdrop Lad.
[Finn then widens his eyes.]
Finn: I can't think of more lyrics! Think Think Think...HURK!
[Finn then barfs out the tiny people and pours the serum on them, making their real bodies awake.]
Finn:Are you guys alright?
[Jake then takes out the spaghetti and points at it.]
Jake: Bwah Bah Blah Bwah
Finn: Uh oh.
Everybody except Finn: Bwah Bah Blah Baaah Bwak Bwwwaaam.