Jerome seems to be in the habit of making fun of everything. how do you see his character in this light

The digressions also help to characterize J. Because the plot ofThree Men in a Boat is so tightly focused on George, Harris, and J.’s trip down the river, J.’s digressions and flashbacks give readers a chance to learn about his past and his personal qualities.

One thing we learn about J. is that he is a classic unreliable narrator. Jerome conveys this to readers by using dramatic irony – that is, situations where the readers understand what is going on even when the speaker does not. As previously discussed, one example of this is J.'s discussion of his diseases in Chapter 1. Readers are supposed to understand that J. is a hypochondriac, not that he is actually ill. The dramatic irony is not limited to J.’s understanding of his surroundings; it also applies to his tone. For example, J. writes with apparent earnestness that he “can’t sit still and see another man slaving and working” (36). Attentive readers will know from previous chapters that this is not true. The disconnect is meant to show us that J. is pompous and hypocritical, qualities that Jerome tends to play for laughs. Again, this particular point - that people construct illusions to fool themselves - continues to manifest throughout the novel.