Oh look - Sir John Middleton and Mrs Jennings have come all the way from Sense & Sensibility to have a laugh at Elizabeth's expense. Of course, they are laughing at the end of the chapter. There is humor in the first half of the chapter, of course, but it is on Jane's part, and based in such good-heartedness that it isn't entirely laughable.
Quick! Into the shrubbery!
Elizabeth drags Jane into the shrubbery (a word which here means that they are walking in the gardens and have decided to hide out, probably on a bench, somewhere along one of the walks - they have not, in fact, tunneled into the hedge) in order to tell her all about what Mr Wickham has said. Jane shows some prudence in questioning whether Wickham is telling the truth. Jane's primary concern is that her Mr Bingley not be such a poor character that he'd be close friends with Darcy, knowing that Darcy had behaved reprehensibly by not acting in accordance with his father's wishes.
Remember when Mr Collins sent his ridiculous letter saying that he had spent quite a bit of time wondering whether he ought to write to Mr Bennet because it might upset his dead father? Yeah . . . while that's really very funny, it shows Collins acting out of a surfeit of deference to his father's wishes. He would not want to do something that he was convinced was completely against his father's wishes. Since his father never told him not to contact Mr Bennet, he decided he could go ahead and do it.
I bring this up because if Mr Wickham's story is to be believed, Mr Darcy has acted in a manner completely contrary to his father's expressed desire. The elder Mr Darcy wanted to leave a church living to Wickham, and the current Mr Darcy has given it to someone else, and not to Wickham at all. To behave with such disrespect to his father's wishes and memory casts a terrible pall over Darcy, and paints him as quite a blackguard (the pronunciation of this word rhymes with "haggard", btw). No true gentleman would do such a thing, you see, so Elizabeth is now convinced that Darcy is both heartless and a scoundrel. And Jane is concerned about Bingley being subject to the influence of a potentially bad man.
Mr Bingley's ball
The kind for dancing, people. Get your minds out of the gutter. (Also, presumably he has two, you know?) But I digress.
On Wednesday, Mr Bingley turns up in person with his sisters to invite the Bennets to a ball the following Tuesday. The Bingley sisters speak mostly to Jane, a wee bit to Elizabeth and not at all to Mrs Bennet or the younger Bennets, but that does not prevent Mrs Bennet from saying plenty to them - and the Bingley sisters hop up to get the heck out of there in order to avoid Mrs Bennet, startling their brother, who was perfectly happy to sit there longer.
And then it rains for days, so the Bennet girls are all stuck at home. And Lizzie, sure that she's going to dance with Mr Wickham for the first two dances, is in high spirits. Spirits so high, in fact, that she decides to amuse herself by talking to Mr Collins, having fun at his expense by asking whether it's appropriate for him to go . . . only to have him decide that going is entirely appropriate, and so is dancing, and by the way, would Elizabeth be so kind as to favor him with the first two dances?
Mr Collins does not stop there, however; he indicates that he's skipping past Jane in favor of Elizabeth for a very particular reason (wink wink, nudge nudge). And Elizabeth starts to realize that he might be thinking of her as a potential spouse - a suspicion that is corroborated by Mrs Bennet telling Lizzie that she believes Mr Collins and Elizabeth are likely to be married. Elizabeth wisely defers having an argument with her mother until such a time as Collins actually proposes, hoping that she's wrong and he might not get around to it.
Mrs Jennings and Sir John cannot stop laughing at the fix Elizabeth finds herself in, and neither can I.