Lucy finds out that she's gained 22 pounds since she got married 10 years ago. But that doesn't stop her from wanting to be in Ricky's new show. Trying to find any excuse he can to keep Lucy out of the act, Ricky tells her that's she too fat to be in the act, since she can't fit into the size-12 costume. Lucy asks if she can do the number if she loses enough weight by Saturday night. Ricky agrees, as a way to shoo Lucy away from bothering him.
Ever determined, Lucy goes on a mission to lose 12 pounds in 5 days. She does everything from jumping rope to running laps around the apartment building to starving herself with a celery-only meal while the Mertzes and Ricky eat a delicious dinner of steak and potatoes. By Saturday, Lucy still has some weight to lose, so she rents a steam box and stays in there all day. Weak, malnourished, and dehydrated, Lucy has lost enough weight from the steam treatment in time for the number at the club.
At the Tropicana, Ricky is surprised when none other than Lucy comes out to perform during the Sally Sweet portion of the Cuban Pete number. The two dance fabulously, and Lucy does a bang-up job. Sadly, after the performance, she is laid up on a stretcher, suffering from weakness as a result of starving herself all week. Before she is wheeled away, she gives a key to Ethel and motions for Ethel to open the nearby closet door. Ethel finds out how Lucy was able to procure doing the number with Ricky- the girl who was supposed to do the Sally Sweet number is bound and gagged inside the closet.
- The "Cuban Pete/Sally Sweet" number Lucy and Ricky perform was taken straight from the tour Lucy and Desi did in 1950, as a way to show/convince CBS that the American public wouldn't find it hard to believe that American-born Lucy was married to a Cuban. Even Lucy's green Sally Sweet outfit is the same as in the original act, feathered hat, sequined purse, and all.
- This is the first time Lucy does her "eeugh" noise to signal she's in big trouble. The writers named this sound the "spider," because Lucy first invented the sound when she played Miss Muffet in a radio commercial for Jello, the sponsor of My Favorite Husband. Besides "spider" (sometimes referred to as "spider-combined-with-the-go-bloots-voice" as a reference to how it was done in episode #16), the writers often wrote many other key words/codenames for common expressions Lucy should do in a particular scene. This list included "the Credentials Look" (referring to the "credentials" line from episode #6), "puddling up" (referring to Lucy's eyes welling up with tears before having a crying fit), "foiled again" (referring to Lucy's expression when one of her schemes took a bad turn), and "light bulb" (referring to Lucy's expression during one of her brainstorms).
- Mattel recently released a two-doll Cuban Pete/Sally Sweet set in honor of the 60th anniversary of I Love Lucy and the last doll in the long-running I Love Lucy season. A two-doll "Lucy Is Enceinte" set was released for the 50th anniversary back in 2001.
- Lucy weighed 110 pounds when she got married. She gained 22 pounds over 10 years, and now weighs 132 pounds now. To fit into a size-12 dress, she needs to lose 12 pounds in five days and get down to 120 pounds.
- This is the first time we hear the use of Lucy's maiden name, McGillicuddy. Her maiden name was originally going to be "Teitelbaum," but was deemed "too Jewish."
- Lucy's scale is oddly precise; it even measures ounces.
- This episode's plot, like so many season 1 episodes, was mostly based off of an episode of My Favorite Husband, but it fit at the time because of how Lucy had just recently given birth to Lucie and hadn't lost all of her pregnancy weight yet.
- This is the first and only appearance of the Mertzes' dog, Butch.
- This episode was rerun in season 2. The new "flashback" opening has Ricky talking about how Lucy has been working out a lot at the gym, trying to get her pre-pregnancy figure back. This leads in to the memory of the last time Lucy went on a diet.
- Ricky ate more oysters than anyone else, because he has the most "R"s in his name.
- Fred: I only ate 12 oysters.
Lucy: (to Fred) [You ate] 16 [oysters], but who's counting? Ethel: Fred, did you really eat 16 oysters?!
Fred: You heard what the oyster counter said! But I was doing it for you! I was trying to find you a pearl!
- Ethel: (to Lucy) On behalf of our tubby trio, I welcome you to our flabby foursome!
- Ethel: Aw, Lucy, don't cry about it. What if I cried every time I gained a pound?
Fred: We'd be up to our ears in tears!
- Snobby dancer: (to Lucy) Can I give you a tip? I've known Ricky Ricardo for a long time. You're not his type!
- Ethel: We'll get you into a size 12.
Lucy: Yeah, a size-12 shroud!
- Lucy: I'm a strong as a very weak horse...
- Lucy: (singing) My name is Sally Sweet. I'm the Queen of Delancey Street. When I start to dance, everything goes chick-chicky-boom, chick-chicky-boom!