Rotund, red, and ready to refresh, the Kool-Aid Man has been destroying walls, scoreboards, and other expensive-to-replace stuff for over 30 years, all in the name of quenching thirst.
The Kool-Aid Man is a huge anthropomorphic pitcher filled with some red substance which may be either Kool-Aid itself, blood, or something else entirely. In the 70's and 80's he cavorted around naked while holding a pitcher filled with Kool-Aid, which carried a kind of cannabalistic meta subtext. However, with the onset of the 90's and its more PC mindset, the pitcher was dropped and the Kool-Aid Man covered up his non-existent unmentionables with some pants. Even today, he is often seen wearing some type of Hawaiian-patterned ensemble, presumably to imply that drinking Kool-Aid is as refreshing as a tropical vacation.
At the height of his popularity in the early 80's, the Kool-Aid Man branched out into comics and video games. In both he fought against an evil race of sunbursts called the Thirsties, who existed to make people thirsty (natch) and just mildly ruin the fun of summer gatherings everywhere. In his comic series he was seen in such various juxtaposed situations as fighting the Thirsties in space and meeting Benjamin Franklin. In his video game for the Atari and Intellivision, the Kool-Aid Man was able to battle the Thirsties much more directly by bumping into them.
Today, he has been recently seen as a recurring joke in Family Guy and the subject of some Dane Cook riffs. And true to his nature as a timeless figure, you can read the Kool-Aid Man's Twitter here. (May or may not be the real Kool-Aid Man.)
Kool-Aid Man's true defining characteristics are his inability to use doors and his infamous battle cry.
Busting Through Walls
When answering the calls of thirsty kids, the Kool-Aid Man lives by the mathematical philosophy "the shortest distance between two points is a line." Busting through and annihilating any structure between him and his target, he is the type of superhero that favors solving short term problems and not long term ones. The Kool-Aid Man of the present is less likely to bust through walls and is instead usually seen hosting some pretty sweet parties.
Far more famous than busting through walls and much less dangerous is the Kool-Aid Man's bellowing catchphrase, "OH, YEAH!" It was usually used in tandem with his former wall-busting but can also be used anytime as an affirmative phrase. It struck fear into his enemies the Thirsties and reinforced his nature as a positive, kid-friendly figure. Kids were able to use the related phrase "Hey, Kool-Aid!" to summon him when they were thirsty.
Before he had arms and legs, the Kool-Aid Man was just a normal perspiring pitcher with a smile drawn on its face, known as Pitcher Man. Pitcher Man existed from 1954 to 1975, when the contemporary Kool-Aid Man took shape.