As the "three men" decide what to pack, J. tells an anecdote about the time he made the ill-fated decision to deliver some incredibly stinky cheese for a friend. He combines verbal irony and hyperbole to amplify the comic effect of this tall tale, where his good intentions end in disaster:
I called for the cheeses, and took them away in a cab. It was a ramshackle affair, dragged along by a knock-kneed, broken-winded somnambulist, which his owner, in a moment of enthusiasm, during conversation, referred to as a horse. I put the cheeses on the top, and we started off at a shamble that would have done credit to the swiftest steam-roller ever built, and all went merry as a funeral bell, until we turned a corner.
The reader can feel the verbal irony in J.'s tongue-in-cheek description of the cab's speed, referring to it as a "shamble that would have done credit to the swiftest steam-roller ever built." Steamrollers are deliberately slow, so the language he’s using is contradictory for comic effect. This ironic statement speaks to the infuriatingly sluggish pace of the cab, which is the opposite of what J. had hoped for in order to save time.
The hyperbole of the passage further emphasizes the slow and cumbersome nature of the cheese trip; it's not just the "steam-roller" which is slow. J. goes as far as to say that rather than being pulled by a healthy horse, the cab was "dragged along by a knock-kneed, broken-winded somnambulist"—a sleepwalker. Everything about the journey is humorously, maddeningly time-consuming. Jerome adds insult to injury in his depiction of J.'s frustration by throwing in a simile, saying that the mood of the scene was "merry as a funeral bell." As few things are less merry than funeral bells, this simile only exaggerates the irony of the cab’s dismal progress.
