"Johnny's Big Dumb Sisters"
Season 4, Episode 7B
United States Airdate: December 10, 2009
Canada Airdate: November 26, 2009
Invention(s) Featured: The Uranium Cranium Mind Builder
Episode Guide
"Johnny's Amazing Cookie Company"
"My Johnny Guard"

Johnny's Big Dumb Sisters is the 92th episode of the Johnny Test cartoon and the 14th episode of Season 4. It first aired in Canada on November 26, 2009 on Teletoon, and in December 10th, 2009 on Cartoon Network.


The twins' latest invention accidentally makes them dumb right before their scholarship interview, and Johnny has to find a way to make them smart again. Unfortunately the machine is out of uranium and needs more.


The episode begins with Johnny and Dukey entering the lab, as they tell the twins that they mastered paddleball. Susan explains that she and Mary built the Uranium Cranium Mind Builder and that it can make anyone a super genius in one blast. Johnny asks can the machine do something. Johnny and Dukey show themselves hitting each other with the paddleball. Susan and Mary explain to him that was just dumb, to which Johnny replies that they're dumb. Susan then replies, saying that dumb people don't get full scholarships to the Porkbelly Institute of Technology. Mary then explains that is why they, need to demonstrate the mind builder to Professor Slopsink to get another year of free college. Johnny didn't care about that and tries to get the cheese with his paddleball. But under the box were two mice. The evil mouse (Montague) wanted all the cheese in the world. Mary then says that she and Susan couldn't find him so they tested the machine on some mice. And Susan explains that it has a reverse mode: "Really Dumb". Susan then says to Johnny that they only have enough uranium left for one more and that he should throw his toy away before he does something dumb. Johnny tells them right after one more paddleball before swinging the paddle. Susan and Mary end up blasted and becoming dumb in the process.

Dukey gets angry at Johnny for blasting Susan and Mary into "Dumbville", making him say "Oh this is JUST great!" but Johnny tells Dukey this is great and that he has big dumb sisters now. He asks them what 2 plus 2 and this is their answer: 22.

This time, when Johnny was messing with girls telling them to test two pies with their faces, Dukey warns him that if the girls won't turn back to normal there will be no cool inventions for him, no time travel, and nobody will do his homework for him, Johnny immediately decided to help the girls and get some uranium to charge the laser, but when he realized that the girls are all out of uranium, he asked Bling-Bling Boy to help him which he refused and said that he's busy opening his own university: Bling Bling University. Dukey reminded Johnny that P.I.T (Porkbelly Institute of Technology) has enough uranium to charge the laser so they took the laser and the girls there and accidentally appeared right in front of professor slop sink, who wanted to take a scholarship test from the girls, Johnny tried to avoid and distract him by saying there's a shaved yak right behind him, which he easily got tricked and he ran off with the girls.

Johnny once again while running with girls, contacted with Bling-Bling with his wrist watch phone, only to found out that Eugene 's at HIS OWN university (bling-bling university) with his classmates who were robots and he programmed them to be his friends and again he refused to help them.

When they got to the University Lab, they found the uranium, only to found out it was in a locked room, while they were trying to open the door, girls (who now were dumb) accidentally activated core meltdown (which will destroy the P.I.T by pushing the "colorful buttons". Johnny tried to fix it, only to make it worse and make the countdown faster. when he turned back he suddenly realized that the girls were gone.

Johnny found them at the Professor Slopsink's office where he was trying to explain to the girls that if they don't pass the test right now, they'll be kicked out of the University and have a horrible life. Johnny tried to distract the Professor by the same trick, which Professor didn't fell for it for the first time but after Johnny repeating it he got distract again and Johnny took the girls and ran out, but this time the Professor catch them fast. After some moments, the meltdown countdown alert activated and professor got the point after Johnny explained for him the whole story and begged professor for help to stop the meltdown. unluckily Professor suddenly fainted from the stress and Johnny begged Bling-Bling for help on his wrist watch phone one more time, this time telling him how sad that is that he programmed his own classmates Bling-Bling broke down, telling him that he don't want to go to school with robots anymore. Johnny explained that he can save Susan and his favorite university instead and he's the guy who always chooses what's right and save the school for love (although he didn't said that by him self and he just read loud what Dukey just wrote on the paper) Bling-Bling got heroic and accepted to help Johnny and got himself there by his jet pack. when he got there he opened the room full of uranium by his laser pointer and Johnny quickly putted the uranium in the laser and made the girls smart again. The girls quickly stopped the self destruction. The Professor suddenly become conscious and thanked the girls and congrats them, giving them their scholarship (for not only making that laser and stop the meltdown, but also living and actually surviving with Johnny) Bling-Bling also apologized the Professor for what had he done in the past and begged him to let him back to the P.I.T, promising not to make anything else to eat up Professor's other and only hand.

The next day, Bling-Bling (who has been accepted again in the University) started goofing up again by bringing pizza to the class and ask Susan out (which again got a big "NO"). when eventually Montague jumped from the window and stole some slice of pizzas from Bling-Bling, bringing them to Johnny and Dukey (who were outside of the P.I.T) while yelling "I'VE GOT THE CHEESE!".







  • Running Gag Susan and Mary Test act dumb for the majority of the episode.
  • This marks the debut of Montague.


  • After Johnny steals the girls video watch (after they became stupid) his watch is gone but in other scenes he has his watch and the video watch one on each arm, or he has just his regular watch and in one brief scene he doesn't have either of the watches.
  • When the Uranium Cranium Mind Builder is first shown, the lever is positioned between the "Genius" and "Really Dumb" labels. On the red label closeup, the lever is shown around the red one. And finally, when Johnny swings the paddleball hard, the lever is shown to be around the "Genius" label.


Produced by Paul Riley
Storyboard by Kevin Currie
Written by Lazar Saric

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