This is a hard haiku constraint because SLING is unusually flexible: it can be a noun, a verb, an idiom, a bag, a cast-like support, or part of a phrase. That kind of range can help, but it can also tempt the poem into just grabbing whichever meaning fits instead of building one coherent scene. Lari’s “PROUD STEAM train comes. / Nearby SHILL sells medicines. / SLINK back. SLING bag. Board.” is a strong example of handling that well: the constraint words are absorbed into a continuous sequence of movement, so SLING feels like part of the action rather than a visible answer word. Across the set, the stronger poems keep the prompt-solving hidden by choosing one use of the word and giving it a real job inside the poem’s world.