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While everyone's eyes were glued to the Democratic National Convention's stage last night, Hillary Clinton and President Obama were practically falling out of their seats laughing backstage. In a private moment between the president and the Democratic presidential nominee Wednesday night, something so funny was said that Obama literally doubled over chuckling:

While only Obama and Clinton seemed to be in on this particular joke, there were a lot more interactions going on behind the scenes.

Vice President Joe Biden, for one, gave lots of hugs:

Vice presidential nominee Tim Kaine practiced his speech:

And Obama and former President Bill Clinton had a good long talk:

Now, if only we knew what that joke was.