A lot of the humor is based on Japanese puns and shit that don't translate properly into English.
Classic one is "Sup Zura"-"NOT Zura, Katsura!" While in the Japanese, this joke is a play on words for "zura," meaning toupee or wig, in the English version, they changed it to "Sup Casserole,"-"NOT casserole! Katsura!" because that's the best they could do, I guess. It'd be impossible to preserve the joke exactly as it is in the original.