It's wrong to get angry over petty things.
Kel is at a birthday party where they are handing out slices of cake to everybody, and he notices his piece of cake is smaller than the rest.
Kel wants to enjoy his cake.
Kel savors each bite of the piece of the cake he got, and he complements the person who made it.
Kel decides his enjoyment of the cake is dependent on him receiving a piece as big as the others and makes a big scene about the size of his piece.
Kel is able to appreciate what he has and ends up satisfied because of it.
People are taken aback by the amount of anger Kel is showing over something so trivial and his standing among his peers drops.