Verbal irony plays less of a role in David Copperfield than in some other Dickens's novels because there is no omniscient narrator to comment wryly on the characters from a remove. Nonetheless, verbal irony is one of Dickens's trademarks, and an example of it can be found in Chapter 34, when David finds his aunt in his apartment:
‘Let me draw the sofa here, or the easy chair, aunt,’ said I. ‘Why should you be so uncomfortable?’
‘Thank you, Trot,’ replied my aunt, ‘I prefer to sit upon my property.’ Here my aunt looked hard at Mrs Crupp, and observed, ‘We needn’t trouble you to wait, ma’am.’
Betsey Trotwood explicitly means that she would rather sit on her suitcase than on David's furniture. It is not that she is more comfortable on a suitcase than she would be on a couch, which is what David accepts as her meaning. What Betsey really means is the opposite: there is no saving her from discomfort in this situation. She prefers to be self-sufficient and rely exclusively on her own "property." Despite this preference, she is about to humble herself to ask David if she might move in with him since she has lost most of her own wealth. In fact, Betsey does seem to be sitting on practically all of her own property at once, at least what is available to her. She is supremely uncomfortable and would prefer not to be in David's apartment at all.
Betsey continues her verbal irony when she tells Mrs. Crupp, "We needn't trouble you to wait, ma'am." Betsey is embarrassed about the conversation she is about to start with David. David is renting from Mrs. Crupp, which means Mrs. Crupp is about to become Betsey's landlady, too. Betsey is used to being her own landlady, so this is a step down for her. She explicitly claims to be concerned about "troubling" Mrs. Crupp, but she is using this politeness to thinly veil a request to be left in privacy. Verbal irony often allows characters to insult one another without appearing outwardly rude. Here, Betsey uses it to put everyone else at ease about an awkward situation. She is proving herself to handle changes in fortune with discomfort but with stoic grace. She is only going to ask David for as much help as she must, and she is not going to become as morose about it as someone like Mrs. Micawber.