In one bonus storyline in Dragon Universe, Vegeta goes behind a bush so he can do a Fusion Dance with Goku without being seen "dancing around like a fool." Goku mistakes him for... taking care of business.
Goku: Well, when you've got to go, you've got to go.
Saiyaman...justSaiyaman. His ultimate is merely him introducing himself and pulling off a pose! Do it right and he gets an attack boost. Screw it up and he looks ever so stupid.
The What If? in the first game where Cell accidentally absorbs Krillin. Made even funnier by the fact that his is the onlyWhat If? where the villain loses. And then it turns out it was just a nightmare Perfect Cell was having during the 10 day Cell Game waiting period.
Yamcha goes up against Cell after he's been weakened by absorbing Krillin... and stillloses.
One small one in Frieza's What If? after killing Goku. He's standing there panting...and then merely grins and "Hmph!"'s...and it turns out after all that, the only damage Frieza truly suffered was that he lost a single tooth.
Goten's winpose after beating Videl. He looks so adorably concerned that Gohan'll be angry at him.
The way some pre-fight dialogue can match up even if the characters don't have special intros. case in point...
Majin Buu: Do you like chocolate? or Yamcha: Think you can handle this?
Kid/Teen Gohan: I'll give it a try!
Some of the special intros, especially...
Goten: (dancing around) Shenron, I want candy!
Omega Shenron: (Folding arms, not amused.) I don't grant wishes for candy!
On the subject of failed attacks, if you fail Yamcha's Spirit Ball attack, his opponent will dodge every hit, then the Spirit Ball will outright spike the poor desert bandit in the face.
Hercule is just as much as a hoot in the Budokai games as in the anime: the first two games turn his giving a bomb-laden handheld video game (as seen in the Buu saga) into one of his Ultimates. Budokai 2 gives him a move wher eafter failing to flinch them with an attack, starts sucking up to them, distracts them with the "LOOK OVER THERE!" gag, knocks them down and puts a camera and tripod up before planting his foot on their prone body, getting a photo from it. Budokai 3 skips straight to the good part.
"Risking It All For A Friend" can be applied to every character in Burst Limit, meaning you get such iconic moments as Goku being saved by Broly.
Super Buu in Budokai 2 has Absorption as his ultimate, where he absorbs either Piccolo, Gotenks or Gohan for a power boost and new Ultimate. In Budokai 2 he can also absorb Vegeta, Cell, Frieza and Tien and Yamcha simultaneously. The funny comes from when he absorbs Tien and Yamcha, getting a new form with Tien's outfit and Yamcha's scars...and a drastically lower power level since he shouts out a disappointed "No!"
And if you look in practice mode when you do it, you'll see that Buu's power decreases (instead of increasing when he does other characters) when he absorbs the two.
This gem when cell does his Spirit bomb ultimate in Budokai 2 and 3 onward
Cell: Okay, planet, gimme that stupid energy!
Alternatively, if you use the Spirit Bomb in the first Budokai Game:
Cell: THANKS FOR THE ENERGYYYYYYYY~!
In Budokai 2 during Krillin and Android 18's second dialogue in Dragon World, Krillin shouts at the top of his lungs that he loves her and asks her to be his girlfriend. Shocked, 18 rejects his offer, but tells Krillin that he's not afraid of the direct approach.
The PAL version of the first Budokai had some hilariously awful subtitles; the emotional impact of Cell killing Trunks is all but destroyed as Vegeta yells "Oh you Aunt Sallies!!"
Goku's different reactions to the various Saibamen encountered during Budokai 2's Dragon World mode.
In Budokai 3, if you loose the button press sequence during Videl's ultimate move, then Gohan accidentally knocks the opponent into her. His response is to high tail it out of there!