From the original, the first stage has the "Drop!" game, timing a button push to apply eyedrops to a patient. The final stage has the "Drop?" game (see at around 1:38), which is identical except that the patient is Wario, who shoots eye lasers at the dropper instead of getting the medicine.
Especially in multiplayer of Mega Party Games when your friends don't know you're supposed to shoot a laser while you do.
Yet another one in the original(which doesn't get its own game, sadly). The intro stage has a game with you jumping over a rock, shark, or hotdog on wheels(labeled "Dodge!". The last stage has a version with either a tiny one(which just falls out of view if it hits you) or the car just turning around and leaving(This one labeled "Dodge?".
Also from the original, Sloppy Salon, where you have to leave the man completly bald. The look of sheer rage when the timer hits zero is just hilarious.
In DIY Showcase, Dribble and Spitz are one of the four premade sets. After beating their boss, the next clip shows their car in perfect shape. A couple of seconds later, still in the cutscene, almost everything falls off. The only things left are the Front Wheels, the paint, and the holder for the thing on top with "TAXI" on it. The things with the letters on them fell off. Scene is here at 2:44.
Listen To The Doctor from Mega Party Games can be quite hilarious, given that you have to watch your friends do something rather stupid looking while playing a microgame.
One of Ashley's microgames in D.I.Y. involves eating four fruits by tapping them. However, two of them are fake : a huge red Gag Nose that looks like a strawberry, and some guy's ass as a fake peach. It's as silly and funny as it sounds.
Speaking of Ashley in D.I.Y., her interlude is both cute and funny : it starts off with her wearing a mask. Tapping the screen will cause her to remove it... to reveal several other ones underneath. There's quite a lot of masks, and some of them actually scare Red when he sees Ashley wearing them.
In general, all of the microgames in all of the games are so silly they're hilarious.
In Smooth Moves, the descriptions of the different poses. That man's voice is so soothing, and he's saying some of the silliest things. First he says the name of the pose, then how to hold the controller for it, then says something about it in a style reminiscent of Deep Thoughts with Jack Handey.
In Game & Wario, after 9-Volt manages to beat 18-Volt's score by a small margin, 5-Volt orders them to do their homework before playing again. They do so and quickly rush back to get the game from 9-Volt's mom...only to find out that she played the game and quite literally has more than double the points her son did in the game.
What's more, she's embarrassed that she is better than her son at games.
9-Volt's minigame after that intro, where 9-Volt has to play a handheld videogame in bed while avoiding detection by his mom, who checks in once in a while to see if he's asleep. Besides the usual ways a normal mom can do it, like peering through the bedroom door or looking through the windows, she can also do it by coming out of the TV, The Ring style!
That minigame is preceded by a long-winded Do Not Do This Cool Thing message saying you should sleep early and not emulate what 9-Volt is doing. Sure...
In Ashley's game in Game & Wario, hitting a wall too much makes her angry, forcing you to calm her down by petting her on the touchscreen. What's hilarious is that you can get her just as angry by repeatedly prodding her with the stylus.
The premise of "Ashley" in general is hilarious. Ashley attempts to teleport into an Eldritch Location within the pages of a book. A blowing fan makes the page turn and sends her and Red to a land made out of candy and sweets. Red is delighted, Ashley is pissed.
There's a little gadget in Game and Wario where all you do is shift the gamepad to make a bunch of beans move around to simulate the sound of waves, because you are the sound guy on a movie set. The movie starts as a sappy romance and quickly goes off the deep end when one of the couple turns out to be an alien. The real humor comes from when you stop moving the pad, at which case the actors look at the screen with furious faces whispering "WAVES!" no matter what they were doing before.