Blabbermouth

Summary
Buster learns how to keep a secret.

Plot
Arthur and his friends throw a surprise party for Muffy on her return from Hawaii. However, Buster doesn't learn about it until Arthur calls him right before, claiming that he forgot to invite him. He runs to Arthur's house, just barely making it as Muffy arrives.

Buster is annoyed that Arthur didn't tell him about the party until the day-of, pointing that Arthur has repeatedly forgotten to tell him about several surprise parties lately—he notices that they have a lot of them. Arthur admits that he hasn't been telling Buster because he is bad at keeping secrets. Shocked, Buster denies being a "blabbermouth", only for Arthur to remind him of the times he blabbed about Arthur's underwear nightmares, his crush on his babysitter, his fear of Grotesquely Grim Bunny, the time he liked Love Ducks, and various surprise parties—and quickly realizes that they do have a lot of them.

Buster claims that he can change and asks Arthur to tell him a secret, so Arthur tells him that he was born in Transylvania. Unfortunately, Buster blabs it almost immediately while being served ice cream by the Brain. He admits this to Arthur and decides that if he only communicates by notepad then he'll be able to think ahead and not tell secrets. Arthur tells him another secret that D.W. had a brain transplant. Due to breaking his pencil and eventually running out of paper, Buster blabs it to George. He decides that he must not be friend material, only for Arthur to admit neither of the two secrets were actually true, because he didn't trust Buster to keep an actual one. Unfortunately, this just makes Buster angry, as while he wasn't good at keeping secrets at least he didn't lie.

Muffy, who is obsessed with social media, claims privacy is overrated: Buster decides blabbing is actually a good thing and sets up a booth where people will tell him their secrets and he will post them online. George tries telling a secret, only for Muffy to claim "slipping on a banana peel" isn't a good enough secret (not to mention she does not believe it). George tells Buster another secret, but just out of pity for Buster.

Buster meets with Arthur, admitting that he did a bad thing, and he wants to stop Muffy from posting George's secret. They head to her house, where Buster just manages to stop himself from revealing George's secret on being asked by Arthur, only for Muffy to tell them that she decided not to post it because it would be mean to George. Buster apologizes and decides best friends don't actually have to tell each other everything, like the fact that he has a little brother. Arthur is at first shocked that Buster never told him...only for Buster to admit that he was joking.

Characters

 * Buster Baxter
 * Slink (cameo)
 * Arthur Read
 * Jenna Morgan
 * Francine Frensky
 * Muffy Crosswire
 * Maria (cameo)
 * George
 * Brain
 * Sue Ellen (cameo)
 * Rattles (cameo)
 * Jane Read (mentioned)
 * Grotesquely Grim Bunny (mentioned)
 * Sally MacGill (mentioned)
 * Fern Walters (mentioned)
 * D.W. Read (mentioned)

Trivia

 * Moral: Don't be a blabbermouth for your own benefits.
 * Timeline: Arthur mentions when Buster told on everyone for ripping his underwear.

Episode Connections

 * The plot of this episode is similar to The Secret About Secrets.
 * Buster also was left out in The Balled of Buster Baxter.

Error(s)

 * Possible/Plot Hole: Rattles is seen having ice cream, but in some episodes, Rattles is revealed to be lactose intolerant.

Home video
DVD: Believe in Yourself!