This whole scene. I ripped the audio and put it in my iPod. It makes me laugh every time.
Kaiba: "You may have beaten me before, Yugi, but this time, I have the upper hand. I've placed my faith in the Heart of the Cards, and without Exodia, you have no chance of overcoming my unstoppable Blue Eyes White Dragons."
Yami: "Yeah, well, at least I'm not adopted."
Kaiba: "What. Did. You. Just. Say."
Yami: "Sorry, did I touch a nerve? Why don't you run home and cry to Mummy? Oh, that's right, you don't have one."
Kaiba: "Yugi, I respect you as a duelist, but if you continue to act like a petulant child then?"
Yami: "Hey everybody, look at me! I'm Seto Kaiba! I have a dragon fetish and I sound like Brock from Pokemon! Screw the rules, I'm in love with Nurse Joy!"
Kaiba: "That's it, Moto, you're f**king dead."