[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/l33t.jpg]]
[[caption-width-right:350:'''[[LeetLingo WH0 KN3W T3H SHR00BZ LUV L33T M3M3Z?]]''']]

* Baby Bowser's line to Baby Mario before their boss fight at the start of the game.
-->'''Baby Bowser: '''Your turn, Super Diaper Bro.
* The sheer fact that Luigi's ButtMonkey status is cranked higher. It's made hilariously worse when his past self does most of the abusing, and even ''laughing'' as he does so!
* Luigi's [[https://www.youtube.com/watch?v=05KQHmMFRKM&t=11m44s incredibly frantic reaction]] when the first time hole that takes them back to the past disappears.
* In general, [[FunnyBackgroundEvent anything the babies do in cutscenes]], since they often can't be bothered to pay attention to what's going on or take it seriously.
* Mario using Baby Mario to attack Petey Piranha.
* Luigi's repeated failed attempts at trying to run away from Sunnycide.
* The "[=L33T HAMM3R=] BROZ."
-->'''Hammer Bro:''' WE R TEH SHROOB ALLIES. WE ROXOR U AND THEN ROFL. THEN U AM CRY.
** After you beat them...
--->'''Hammer Bro:''' ''[[LampshadeHanging Seriously, who talks like that??]]''
* The moment Toadsworth sees his past self with Baby Peach, he instantly assumes that his younger self has de-aged Peach into a baby and kidnapped her, and starts chasing him around. Even when he figures out the truth, he just can't get along with his past self. On a related note, their attempts to cheer Baby Peach up are also pretty funny. The Mario Bros even use these to learn new moves.
** To add to the hilarity, Elder (present) Toadsworth get more and more aggravated at the physical toll that demonstrating the moves is having on him until he outright sits out of the last tutorial. He spends the rest of the game until the ending in baby Peach's stroller, apparently still in shock of flattening her before said tutorial.
* As Baby Bowser is going on a tangent about why the Mario Bros. are technically the bad guys, the baby bros. are busy eating from the massive pile of cookies that baby Bowser had for himself. Then he notices them as they are finishing up the last few crumbs.
--> '''Mario, Luigi, & Kamek:''' [[{{Beat}} ...]]\\
'''Baby Bowser:''' '''[[BigWordShout OH NO!]]''' STINKY BABIES!
** Made even more amusing by the fact that Baby Bowser jumps when he shouts "OH NO!" and the word bubble goes up with him, before flying off of the screen.
* After falling into the secret caves under the Koopaseum, the babies attempt to wake up their unconscious adult selves. Baby Mario's solution [[TheAllSolvingHammer (as usual)]] is to hit Luigi with his hammer. This does wake up Luigi, but he (understandably) gets furious and gives Baby Mario a stern scolding, which causes him to start crying, with Baby Luigi immediately following suit. While Luigi [[OhCrap panics]], Mario wakes up and sees the babies crying, not knowing what happened. He then takes it out on Luigi and angrily reprimands him, [[EverybodyCries causing him to start crying loudly with the babies]] and resulting in Mario sighing in confusion or exasperation over what just happened, like he's thinking "Geez, what am I gonna do with them? It's like I have three baby brothers!".
* The Star Gate's insinuating that Luigi is not pure of heart and cannot go through him, dangling a certain "secret" of Luigi's that the Gate claims is scandalous. Also, it claims that Mario should really eat more healthily than he does.
** Some elaboration: The Star Gate declares that Mario's heart is pure and full of virtue and courage, then he goes on to criticize Mario's diet and waistline. It comes across as though the only negative thing you can possibly say about Mario is that he's kinda fat.
** A bizarre mix of heartwarming and funny: at the end of the Aurora Block section, the Star Gate tells Luigi that, with his self-value realized, he may now hit the Aurora Block. After the glorious moment of Luigi finally being able to do so, the Gate mentions that another quality of the block is that it matches the size of the heart of whoever strikes it. Cue the suddenly massive block falling from the sky and flattening Luigi.
* If saving upon entering Gritzy Desert for the first time, the save file description reads as follows:
--> Huh? [[ShiftingSandLand Sand, sun, heat...a desert?]] Are the Shroobs here, too? No worries! [[BringIt Mario and company are ready to take on anything!]] [[TemptingFate Bring on the Shroobs!]]
** And then the moment they set foot through the front door of the Koopaseum, they're [[OhCrap chased out by a small army of them]]. Bring on the Shroobs, indeed!
* While Kylie Koopa questions Mario in a little "interview", Luigi and the babies [[FunnyBackgroundEvent are having a Benny Hill-esque routine with the Shroob]].
* When talking to the Toad wandering around in the shop area during early game, you'll find out that reception for their most popular item, the mushroom, ranges from "Rich flavor!" to "Great Texture" to... "Gross".
* In the Thwomp Volcano, we finally get to see what a "female" Thwomp looks like... A round boulder with a face bearing crooked teeth and a massive unibrow. That you fight as a boss. Because she and her husband didn't go on what was their equivalent of a vacation (jumping into an active volcano).
** And then there's her husband, a Thwomp that the bros. climb on to get into the volcano, telling her that she's too heavy for him to carry into the volcano. She then proceeds to violently knock him into the volcano while calling him a jerk.
*** Just before that, there was when everyone tries to climb the Thwomp in the first place. Luigi jumps up in spectacular fashion and starts dancing. Then Mario helps his past self up and gets on himself. The Marios then stare at Luigi, who stops dancing for a bit before he realizes that he forgot to help his past self get up, and Baby Luigi is now trying to climb the Thwomp's face.
* The Bros enter the Star Shrine and when the player collects the fourth Cobalt Star Shard, and suddenly Kylie and Toadbert fly in via Lakitu. The mere fact that Mario and Luigi had to go through these trials and puzzles to enter the Star Shrine yet there is a Lakitu taxi service that anyone can use to fly up there will leave you either enraged, or dying of laughter!
* Right before entering Shroob Castle, Stuffwell gives everyone a pep talk, which culminates into everyone posing dramatically. Except for Luigi, whose response is a classic Luigi-esque "No". After an intense staredown with everyone else, Luigi reluctantly agrees to go with them.
* On the Shroob Mothership, after Kylie Koopa accidentally opens up a trap door, the Bros all fall with terrified looks on their faces, and all start screaming in horror... except for Adult Mario, [[ThrillSeeker who shouts "Yippee!" instead.]]
* If you don’t have any Green Shells for the tutorial battle against the Goomba summoned by Kamek, he will proceed to give you Green Shells by accident before summoning the Goomba.
--> '''Kamek (first time)''': Wait, that's wrong! AAAACK!
--> '''Kamek (second time)''': Hang on! I messed up! YAAACK!
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