All Parody cards are Illegal for the fact that they have stupid, overpowered or impossible effects (such as, Tokens are Special Summoned w/o card effects) they often have absurd lores, Levels, ATK/DEF values, and most of them, have the LAUGH attribute and Charisma-Type.
For instance, Kataria, Tower Tofla of Evil Vine (Illegal) was basically a parody of the Synchro Monster Kataria, Towers Tofla of Evil Vine, for the fact that it actually has an ATK and Level values would exceed the maximum Values of Any Normal Monster in real game.
Problem? is a Parody of for the fact that many players don't read the card's effect, and they get upset about having their card effects negated instantly.
U Mad Bro is a Parody of due to its effect that allows its player to negate any activation of a card. many players have raged towards Cyber Dragon Infinity for being splashable in almost every deck, while the the main cause of the problem was actually " "