"Resumé" cuts right to the chase: in the first four lines of this short, snappy poem, a speaker considers and rejects four different suicide methods. That might sound grim, but everything about the way this poem is shaped makes it clear that this speaker is telling not a tale of despair, but a pitch-black, ironic joke.
First off, there's the speaker's ridiculous understatement. In real life, any of the suicide methods the speaker describes here would be agonizing; in this poem, they're presented simply as inconvenient. When the speaker objects that burning yourself to death with acid would "stain you," for instance, it's as if they're tsk-ing over the laundry bill they'd rack up, not trembling in fear over a horrific demise. The same is true for the unpleasant "damp[ness]" of rivers and the "cramp" of an overdose: these mild objections sound like the words of a parent warning a kid not to go swimming too soon after eating, not a person in despair.
All this ironic understatement also starts to paint a picture of a person who's so jaded about life that even suicide just sounds like a bit of a chore.
Notice how the way the speaker uses parallelism and end-stopped lines throughout the poem to make it seem as though the speaker is rejecting suicide methods as easily as one might decide against choices on a menu. The speaker begins each straightforward line by introducing a suicide-adjacent noun (razors, rivers, acids, drugs) and then wraps things up quickly and definitively, leaving no room for argument.
The accentual meter here makes the speaker sound even more casual. Accentual poetry doesn't use any one kind of metrical foot; instead, it just uses a certain number of stresses (or strong beats) per line. Each of these lines uses a mere two stresses, like this:
Razors pain you;
Rivers are damp;
The combination of a strong beat and a changing rhythm means this speaker sounds both firm and casual: both attitudes one wouldn't necessarily expect from a person contemplating suicide!
In just 13 witty words, then, the first half of this poem creates a dramatic situation and paints a vivid portrait of a drawling, jaded speaker whose feelings about suicide seem to be, in essence, "But it sounds like such a bore." This is all funny in itself—but it's also clearly the setup to a joke, and readers can feel that a killer punchline is on its way.