Jennifer Lawrence was supposed to appear on 'The Late Show With David Letterman' earlier this week, but she had to reschedule. She showed up tonight (Nov. 20), and it was worth it. America's Girl Crush was adorably and incredibly neurotic.

She joked that they will be making as many 'The Hunger Games' sequels as 'Now That's What I Call Music!' series has (aka the 'Now!' CD compilations, which collect the biggest pop hits on one CD and are up to, like, Vol. 123 at this point). Actually, they're at Vol. 86.

The actress had to reschedule her appearance because she had a stomachache for three weeks and thought she had an ulcer and had to have it checked out. It wasn't an ulcer -- she called it a "fulcer." She had an endoscopy and called herself a a "head case" and "crazy." Lovably so.

The interview, as Letterman said, was running of the rails, since the actress was rambling in the cutest possible way. Her thoughts were anything but linear, and she wasn't kidding when she said was exhausted from all the promo and red carpets. J. Law was cold on set, so they gave her a big, pink comforter to wrap herself in.

Still, a sleep-deprived, overworked J. Law, who joked that "they" give her a shot in the butt before sending her onto the red carpet, is adorbs.

She also talked about crapping her pants multiple times, so you'll want to watch this clip.

Watch Jennifer Lawrence on 'Letterman'