The part in the book (and the movies) when Mrs. Bennet asks Mr. Bennet to force Elizabeth to marry Mr Collins, only to have him turn around with this line:
"An unhappy alternative is before you, Elizabeth. From this day you must be a stranger to one of your parents. —Your mother will never see you again if you do not marry Mr. Collins, and I will never see you again if you do."
When Elizabeth relates Mr. Wickham's tale of woe to Jane, Jane will not believe that Mr. Bingley's dear friend Mr. Darcy would be as cruel as described, and attributes the whole thing to a misunderstanding between the two men. Jane suggests that "interested people" have misrepresented Wickham and Darcy to each other, prompting a teasing reply from Elizabeth.
The scene at Netherfield where Mr. Darcy is trying to write a letter to his sister and his Clingy Jealous Girl Caroline Bingley constantly interrupts him to compliment his handwriting, the evenness of his lines, observe how fast he writes, or add her own message to his sister... while remaining completely oblivious to her target's determination to ignore her as best as he can!
There's also the scene where Mr. Collins proposes and accepts Elizabeth's answers without her responding. She tries to turn him down gently, but he's not worried. He's heard that some women turn down proposals they plan on accepting. Sometimes even three times. It takes quite a while for her to convince him she's not going to marry him.
The infamous bit when Darcy dives into a lake and thus spawns the 'wet shirt' fetish. That itself isn't the funny part; the funny part is when he comes face to face with the (at the moment) unrequited and unexpected love of his life, basically half naked by the standards of the time and dripping wet. The awkwardness is both palpable and hilarious; Elizabeth's even Distracted by the Sexy for a moment or two! Enjoy! -> https://www.youtube.com/watch?v=hasKmDr1yrA
Darcy's sarcastic expression and rolling of the eyes when his conversation with Elizabeth (and Colonel Fitzwilliam) is interrupted by Lady Catherine.
Elizabeth providing occasional riffing on Darcy's letter. "I look back with regret on only one aspect of my behavior in this matter..." "Oh, really? Astound me."
Any time Caroline says something cutting about Elizabeth, and Darcy manages to turn it around and use it to insult Caroline.
"Other way, Mr Collins!" Poor Lizzy...
When Bingley is gushing over Jane after first meeting her, Darcy replies with a gruff "she smiles too much."