The narrator speaks over a montage about women heading out to help out the male soldiers fighting during World War II in works such as building, wielding, riveting, and making the war weapons such as guns, shells, tanks and planes to supply the needs of the WWII soldiers. In the process, strong women were born who had overcome all problems, obstacles, and difficulties... except for just one problem: who would take care of their children while they're working during the war.
Eventually, a mother hires a clueless Porky Pig to babysit her child while she works at the factory, giving him a Child Psychology book as a guide. Porky quickly finds out that the baby is a violent-tempered infant named Percy, though Percy names himself "Butch". Porky's first encounter with Percy/Butch doesn't start off quite well: when he is playing cards in the pram, he tells Porky off "LET'S NOT GET NOSEY, BUB!" and then pushes Porky away, and just as Porky gets to know his name, he mocks Porky's stutter, and drops an anvil on Porky's head, sending him multiple floors down into the basement. Porky, now stuck in the basement, reads the book's contents:
- Give baby a cat and watch his little puss light up: Porky gives his unnamed pet cat for Percy/Butch to play with, however Percy/Butch scares the cat out of his wits, catches it, and starts jumping around it like a skipping rope. Shocked that he is committing animal abuse, Porky scolds him to let go of the cat, and he eventually (literally) lets go of the cat. The cat tries to walk away, but feels dizzy going in circles due to the aforementioned experience.
- Next, Percy/Butch is reading a racy adult magazine known as Exquire Junior. When Porky points out that Percy/Butch is too young to read such magazines, he bites Porky's finger twice, and Porky struggles to get him out of it. Half-way, Porky reads through the Child Psychology book's contents, "Not only will he eat your finger, a kid'll eat ivy too, wouldn't you?"
- Eventually, Porky successfully gets Percy/Butch off his fingers, which sends the infant crashing into some pots and pans in the kitchen. Percy/Butch then declares "Of course you know, this means war!", launches into a Winston Churchill impression, complete with a V sign with his fingers while holding a cigar in the V sign, stating "We will fight until Hitler and his Nazi gangsters suffer disastrous, overwhelming and complete defeat!". From this point on, Percy/Butch starts violently chasing Porky around the house with a meat cleaver. Porky hides into another room, and skims through the book one last time; to a page saying "Do not hold a grudge - the kids ready to bury the hatchet". Just as Porky reads through the page, Percy/Butch almost strikes the cleaver right onto Porky head, nearly killing him.
Eventually, Porky gives up on the book since none of the book's contents are effective against Percy/Butch, and desperately tries to run for his life. At one point when Porky hides away, Percy/Butch re-encounters the cat which he previously used as a skipping rope, and starts giving the cat a chase with the cleaver, scaring the cat out of its wits.
Percy/Butch's mother returns home from work, and notices him chasing Porky and the cat around the house with a meat cleaver, and asks "What's the matter, Didn't you use the book?" which Porky replies that "Yeah, but it-it-it didn't work!" She then reveals that Porky didn't use the book right, and she spanks the infant with the book, which she finds more effective.
- (1986) VHS - Viddy-Oh! For Kids Cartoon Festivals: Porky Pig Cartoon Festival Featuring "Nothing but the Tooth" (only in Pal regions)
- (1988) VHS - Cartoon Moviestars Porky!
- (1988) LaserDisc - Cartoon Moviestars: Daffy! and Porky!
- (1992) LaserDisc - The Golden Age of Looney Tunes, Volume 2, Side 3. Frank Tashlin
- (2010) DVD - TCM Spotlight: The Errol Flynn Adventures (USA 1995 Turner print)
- When this cartoon aired on Cartoon Network, Boomerang and TNT in the USA, the scene in which Baby Percy impersonates Winston Churchill after he crashes into the kitchen was cut, but Turner networks outside the USA left this scene intact.
- The mother is voiced by Bea Benaderet impersonating Cass Daley.
- Porky finds Butch, called "Percy" by his mother, reading Exquire Junior, a send-up on Esquire, which was considered quite racy then. The magazine pages show infant girls (wearing only diapers) in sexy poses.
- After Butch emerges from a pile of pots and pans with a pot on his head, he launches into a Winston Churchill (see "Censorship" above) impression, stating "We will fight until Hitler and his Nazi gangsters suffer disastrous, overwhelming and complete defeat!" While delivering his Churchill speech, Butch gives the V sign with his fingers while holding a cigar in the V sign.
- The mother works at "Blockheed", a parody of Lockheed.
- When the mother first meets Porky, she asks if he wants her to help defeat the Axis Powers. In the question, she uses the word "Japs", a derogatory term for Japanese people used commonly during World War II. In his response, Porky mentions "Schickelgruber", referring to Adolf Hitler's original surname.
- Porky wears pants in this cartoon, something he would never wear most of his other cartoons. A few other cartoons from the "classic" era where Porky wears pants include "Porky's Badtime Story" (1937), its color remake "Tick Tock Tuckered" (1944) and "Dime to Retire" (1955). Running gags throughout the 2011 spin-off series The Looney Tunes Show would have people ask Porky if he wasn't wearing pants.
- It is most likely that this is first cartoon to have Porky's face without Daffy on the opening bullet-titles.
- "Brother Brat" is the last Porky Pig cartoon directed by Frank Tashlin because he left the studio to direct live-action movies in 1945.
- The cat's scream (voiced by Mel Blanc) heard when Percy/Butch attempts to kill the cat with a meat cleaver near the end of the cartoon is reused in some of Cartoon Network's Checkerboard Era bumpers in 1993 (specifically the end of the "Here's one more reason why you should have the Cartoon Network" bumpers which had the eyes popping out of the two 0s of the 1992 CN logo, as seen in "A Taste of Cartoon Network" 1993 VHS). This aforementioned stock scream by Blanc was previously heard in one scene from "The Trial of Mr. Wolf" (1941) and is even reused in one scene from "Duck Amuck" (1953).
- A 1986 Cartoon Festival VHS print with the altered a.a.p. opening titles similar to the ones seen at the start of Cartoon Festivals prints of "Daffy Doodles", "Hold the Lion, Please" and "I Taw a Putty Tat" does exist, but however it does not appear on any of the USA releases of the Viddy-Oh! For Kids Cartoon Festivals VHS collection: instead it only appears in one of the non-USA releases of the VHS collection, which also includes the Cartoon Festivals print of "My Little Buckaroo" on the same international VHS release.
- An alternate version of the 1986 Cartoon Festival VHS print with the altered a.a.p. opening titles seen in European releases of this VHS collection had the a.a.p. opening titles from My Little Buckeroo plastering over the original opening rings, with the 1941-1955 Merrie Melodies opening music playing over it. This said a.a.p. print airs (as recently as 2018) on Boomerang Italy instead of the 1995 EU dubbed version print, hence making it one of the very rare non-dubbed pre-1948 Looney Tunes cartoon airings on European networks after 1995.
- The copyright was renewed in 1971.