Original air date: November 20th, 1992
At Lancer's home, Patch, Melody, Bright Eyes, and Clover, calling themselves the Dream Team, are all practicing their synchronized swimming in preparation for tomorrow's competition. Sitting on a wall, Teddy insults their skills and throws a rubber octopus into the pool to scare them. Once the girls realize it's not real, they furiously run after Teddy, only to slip. Teddy laughs at them some more until Lancer squirts him off the wall using a hose. Teddy storms off, yelling at the girls that he hopes they lose the competition.
The girls sit around eating carrots, and Sweetheart is excited about her upcoming birthday party. Lancer informs them his parents called home from Shetland Springs and told him they could use the ballroom, so he's having it decorated. When the girls find out Teddy is also invited, they aren't pleased.
The next day at the synchronized swimming competition, the Dream Team's performance goes swimmingly... up until Clover sees what she thinks is a sea monster underwater, causing her to miss a sequence with the other three. She swims to the edge and tells everyone what she saw, and the "sea monster" then surfaces before Teddy removes his disguise. As a result of not finishing their routine, the Dream Team is disqualified.
Sweetheart defends Teddy, but the girls aren't interested, and give her an ultimatum: she uninvites Teddy from the party or none of them show up. Not wanting to pick a side, Sweetheart cancels the party entirely. She talks about it with Lancer, who has an idea.
Lancer invites Teddy aboard his father's private boat and escorts him to a room containing the girls (sans Sweetheart), who also weren't aware Teddy would be coming. The girls say they're leaving, but then the boat leaves. Lancer lays out a peace treaty, calls them out on upsetting Sweetheart with their quarrelling, and tells them no one gets off until the treaty is signed.
On Sweetheart's birthday, she's still upset about having to cancel her party. Lancer, escorting her into his mansion, assures her that she'll likely cheer up when she sees what he has for her. To her surprise, a party is on, and not only are her six friends in attendance, but so is Teddy! The party goes off without a hitch, and Sweetheart is overjoyed.
"Happy Birthday, Sweetheart" provides examples of:
- An Aesop: Personal beefs should be set aside for the benefit of a third party that both you and the other person care about.
- Anthropomorphic Shift: The girls sit around eating carrots and speak of being happy when they'll be able to eat real food again.
- Birthday Episode: The candles on top of Sweetheart's birthday cake are clearly shaped the number 10, and the song mentions it's her "tenth year"note .
- Calling Your Attacks: Lancer after Teddy interrupts the girls at practice:Teddy: (laughter) Nice moves, Dream Team! What do you call that one?
Lancer: Well, I call this one "squirt Teddy with the hose"! (proceeds to do just that) - Crying at Your Birthday Party: Sweetheart cries Tears of Joy upon seeing her surprise party.
- Feud Episode: There's one between Teddy and the girls besides Sweetheart, prompting Lancer to get them to reconcile so they can attend Sweetheart's birthday party.
- Fiction Isn't Fair: The pony in charge of the swimming competition is entirely unsympathetic to the extenuating circumstances behind the Dream Team's failure, and Teddy faces no consequences.
- Friendly Scheming: Lancer forces Teddy and the girls to set aside their quarrel so that Sweetheart can have her birthday party and they can be friends again.
- Grammar Nazi:Lancer: You know what the problem is? You're all selfish. Here you are arguing about who did what to who.Bright Eyes: I believe it's "whom"?
Lancer: Whatever. - Green Around the Gills: Happens to Bon Bon from being seasick aboard Lancer's father's boat.
- Idiot Ball: The girls swimming away from a fake rubber octopus despite seeing Teddy chuck it into the pool.
- I Resemble That Remark!:Teddy: (to Bright Eyes) Well, you're just a little pony who thinks she knows everything!Clover: That's not true! Bright Eyes doesn't know everything!Bright Eyes: I do too!
- It's the Best Whatever, Ever!:Sweetheart: I really truly don't know what to say except that... that this is the nicest, happiest day of my life! Thank you!
- Jerkass Has a Point: Teddy says Bright Eyes thinks she "knows everything", but when Clover says Bright Eyes doesn't know everything she says "I do too!".
- Locked in a Room: Lancer engineers this to force his quarreling friends to reconcile. His version involves stranding the lot of them on his father's private yacht.
- No Sympathy for Grudgeholders: This is Lancer's attitude to Teddy and the girls feuding against one another, since it has resulted in Sweetheart cancelling her birthday party, so he hatches a plot to make them knock it off, thus saving Sweetheart's birthday.
- Surprise Party: Sweetheart is presented with one at the end.
- Take a Third Option: The other girls tell Sweetheart she has to choose between them or Teddy; either uninvite him from her upcoming party, or none of them will come. Sweetheart responds by tearfully canceling the party.
- Through a Face Full of Fur: Despite being covered in fur, Bon Bon turns green from being seasick.
- Uninvited to the Party: The girls demand that Sweetheart do this to Teddy or they won't show up.
- The Watson: When Bright Eyes calls Teddy a rabblerouser, he asks what one is.
- What the Hell, Hero?: Lancer calls out Teddy and the rest of Sweetheart's friends when their feuding leads to her miserably cancelling her own birthday party.
- With Us or Against Us: Sweetheart's friends demand Sweetheart uninvite Teddy from her birthday party or they won't attend.
