People are still talking about what Seahawks cornerback Richard Sherman said about 49ers wide receiver Michael Crabtree at the end of last night's thrilling NFC Championship Game between Seattle and San Francisco. Although the game ended nearly 12 hours ago, "#RichardSherman" and "Crabtree" are currently trending on Twitter. And with good reason. Sherman's post-game outburst was one of the craziest outbursts we've ever seen from a professional athlete. But why did he have it?

The assumption after last night's game was that Crabtree said something to Sherman on the field that got him fired up. But late last night, Sherman finally revealed exactly why he went after Crabtree during his post-game interview. And as it turns out, his outburst has actually been a long time coming. Because according to Sherman, he's been upset with Crabtree ever since last offseason when Crabtree said something offensive to him.

"He said something personal face to face," Sherman revealed last night, without saying exactly what Crabtree said. "He knows what he said and he knows I'm going to be tough on him the rest of his career."

Sherman also continued to bash Crabtree long after the game was over.

"He wouldn't make the top 20 of NFL receivers," he told reporters. "If any team had a chance to pick Crabtree, they wouldn't draft him."

Crabtree did get around to talking a little trash of his own on Twitter:

But by that point, the damage was pretty much done. The rivalry between these two is very real and seems to stem from something Crabtree said to Sherman a long time ago. And after last night, we don't see that rivalry ending anytime soon.

UPDATE:

The Seattle Times may have uncovered the truth behind Sherman's beef with Crabtree. They spoke with Sherman's brother Branton, who revealed that Sherman felt slighted by Crabtree during an appearance at a charity event held by Larry Fitzgerald last summer. Crabtree reportedly refused to shake Sherman's hand at one point, which led Sherman to later say, "I'm going to make a play and embarrass him."

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[via ESPN]