The Paradox Brothers are a pair who like to rhyme, as they do it all the time (but not always successful). They are only seen in "Busted Rhymes", after Bakura found them using his gaydar. There is a possibility they are gay. Their rhyming causes everyone else to rhyme too. They both danced to the Y.M.C.A. music when they first appeared. They have explicitly revealed their sexual preferences, "We invite you to suck on our co-!" and "And we like wearing women's frocks!". They also acknowledged that they are "lame villains" and aren't disappointed when they lost the card game.
Apparently they have to do rehearsals before they can start to rhyme, as shown by the twin brother in green who usually ruins their rhymes: after saying that he wasn't wearing any underpants and saying nose instead of ass. In the 2008 Christmas Special Yugi claims not to want to hear anymore rhymes after his duel with the Paradox brothers, indicating how their lame rhyming made all other rhymes bad to him.
They make a later cameo appearance in DarkSideIncorporated's "Yu-Gi-Oh! GX: The Abridged Series" during episode 9, titled "Brothers from the Hood." At first, they are unable to rhyme, saying, "We are the brothers Para and Dox," "And we love playing a children's card game for money and beating kids like you." Later, they begin to rhyme again, only to cause Syrus to become angry and "throw down" with the Paradox Brothers. The duel soon turns into a rap battle more than a card game, with Syrus' team winning, and Crowler admitting the Paradox Brothers to be the worst cameo ever, as well as stating that Jaden can't rap for sh*t.