This is how Yuna, Snowdrop and Pound Cake believes Norman is a zombie goes in Welcome to Gravity Falls.
We see Yuna, Snowdrop and Pound Cake are in the Mystery Shack's attic.
Princess Yuna: (Reading aloud from Journal 4) Known for their pale skin and bad attitudes these creatures are often mistaken for...teenagers! Beware Gravity Falls' nefarious...(Gasps)
We see the journal page on The Undead. The picture of the zombie becomes Norman.
Journal Norman: 'Sup.
Princess Yuna: ZOMBIE!!!!!
Grunkle Stan: (In the bathroom) Somebody say "crombie"? What is that, crombie? That's not even a word. You're losing your mind.
Yuna, Snowdrop and Pound Cake looks out the window to see Norman walking towards Pumpkin Cake with outstretched arms while moaning.
Pumpkin Cake: I like you.
Princess Yuna: Oh, no! Pumpkin Cake!
Pound Cake: No, no, Pumpkin Cake, watch out!
Norman: Huh, huh! (Puts hands around Pumpkin Cake's neck)
Norman: (Removed arms, revealing flower necklace) Huhhh!
Pumpkin Cake: (Gasps) Daisies? You scallywag...
Princess Yuna: Is my friend really dating a zombie, or am I just going nuts?
Soos: (Screwing in a light bulb) It's a dilemma, to be sure. (Yuna, Snowdrop and Pound Cake gasps) I couldn't help but overhear you talkin' aloud to yourself in this empty room.
Snowdrop: Soos, you've seen Pumpkin Cake's boyfriend. He's gotta be a zombie, right?
Soos: Hmm. How many brains didja see the guy eat?
Pound Cake: (looks down) Zero.
Soos: Look, dude, I believe you. I'm always noticing weird stuff in this town. Like the mailman? Pretty sure that dude's a werewolf.
Flashback of a hairy mailman walking by Soos, who is eating his lunch outside. Soos slightly moves away from him.
Soos: But ya gotta have evidence. Otherwise, people are gonna think you’re a major league cuckoo clock.
Princess Yuna: As always, Soos, you’re right.
Soos: My wisdom is both a blessing and a curse.
Grunkle Stan: (Shouting offscreen) Soos! The portable toilets are clogged again!
Soos: I am needed elsewhere. (Backs out)
Princess Yuna: (narrating) My friend could be in trouble. It was time to get some evidence.
Princess Yuna filming Pumpkin Cake and Norman in the park.
Pumpkin Cake: (Throws a Frisbee at Norman, who fails to catch it and falls over.)
Princess Yuna: (Stops looking through camera and frowns at Norman)
Norman breaking through a door window to open it from the inside and letting Pumpkin Cake inside the diner.
Norman: (Stumbles around and crashes trying to follow Pumpkin Cake)
Snowdrop: (Looks out from behind menu)
Pumpkin Cake and Norman frolicking.
Norman: (Falls into a pit, then crawls out, hand first, screaming)
Pumpkin Cake and Norman: (Pause, then laugh)
Princess Yuna: (narrating) I’d seen enough.
In the Mystery Shack, Pumpkin Cake is brushing her mane and Yuna, Snowdrop and Pound Cake enters.
Pound Cake: Pumpkin Cake!
Princess Yuna: We’ve gotta talk about Norman.
Pumpkin Cake: Isn’t he the best? Check out this giant smooch mark he gave me! (Shows her cheek, which has a swollen spot on it)
Pumpkin Cake: Ha, ha! Gullible. It was just an accident with the leaf blower!
Flashback to Pumpkin Cake with a leaf blower.
Pumpkin Cake: (Putting picture of Norman on leaf blower's tube) Kissing practice! (Leans in to leaf blower, when it sucks in the picture sticks to her face as well. She runs around) AHHH! Turn it off! Turn it off!
Back to present.
Pumpkin Cake: That was fun.
Princess Yuna: No, Pumpkin Cake, listen! I’m trying to tell you that Norman is not what he seems! (Brings out Journal 4)
Pumpkin Cake: (Gasps) You think he might be a vampire? That would be so awesome!
Princess Yuna: Guess again, Pumpkin Cake. Sha-bam! (Holds book open to gnome page)
Pumpkin Cake: Agh!
Princess Yuna: Oh, wait. I'm-I'm sorry... (Flips to Undead page) Shabam!
Pumpkin Cake: A zombie? That is not funny, Yuna, Snowdrop and Pound Cake.
Princess Yuna: I’m not joking! It all adds up: The bleeding, the limp. He never blinks! Have you noticed that?
Pumpkin Cake: Maybe he’s blinking when you’re blinking.
Princess Yuna: Mabel, remember what the book said about Gravity Falls? Trust no one!
Pumpkin Cake: Well, what about me, huh? Why can’t you trust me? (Puts on star earrings) Beep bop!
Pound Cake: Pumpkin Cake, (Shaking her) He's gonna eat your brain!
Pumpkin Cake: (Pushes him away) Yuna, Snowdrop and Pound Cake, listen to me. Norman and I are going on a date at five o’clock, and I’m gonna be ADORABLE, and he’s gonna be DREAMY, (Pushing Yuna, Snowdrop and Pound Cake out of the room)
Pumpkin Cake: And I am not gonna let you ruin it with one of your crazy CONSPIRACIES! (Slams the door)
Princess Yuna: (Sighs and sits down) What are we gonna do?
Pound Cake: Well, There's gotta be a way.
Snowdrop: But how?
Wheelie: Do you have a plan, Yuna?
Brains: What can we do?
Princess Yuna: Well, We should go see what Norman is up to and bring proof.
Snowdrop: What kind of proof?
Princess Yuna: Any kind of proof, Come on.