Hillary Clinton Cracks Up After Michelle Obama Mentions Barack's Nobel Peace Prize

Hillary Clinton broke into a giggling fit during the opening of Barack Obama's presidential library ... cracking up at what might've been a subtle dig at President Donald Trump ... and the punch line is the Nobel Peace Prize.

Here's the deal ... former First Lady of the United States Michelle Obama gave a speech before her husband spoke ... listing his accomplishments and putting a special emphasis on one word in particular.

Michelle said one of her husband's greatest achievements was "winning the Nobel Peace Prize" ... hitting the word "winning" pretty hard.

The crowd broke into a loud, long cheer, and Hillary started laughing ... leaning over to say something to her former boss as well.

While it's not totally clear why the former Secretary of State enjoyed the joke so much, it may be a dig at Trump ... who has said numerous times he wants a Nobel Peace Prize -- and who was gifted one by Venezuelan opposition leader María Corina Machado after he ousted former President Nicolás Maduro in January.

Trump's never actually won it, though ... which could explain why Michelle made it very clear Barack has.

Regardless, the crew seems to be having a great time at the dedication for Barack's presidential library in Chicago ... which will open Friday to the general public.