Okay, can anyone tell me why this is so?

I personally don't know where they all originated but most fans come up with either the most least likely/jacked up pairs to ship or they think one looks cute with the other and they spread it. I think Joey and Kaiba /was/ actually LK, mostly because of Joey's dog suit fiasco but yeah. Um, Duke and Tristan probably because they're both after Serenity so HEY let's pair them anyway. And uh, Pharoah (who is super awesome) and Yugi because, well, they share a body and it can be creepy or....creepier lol. But like I said, most pairings most likely originate from some twisted fan who thinks a certain pairing would be funny or would throw off the entire series....:D