parched wheat or rice, broken grain
糗 centers on grain that has been dried or parched, resulting in broken or coarse pieces. It refers to parched wheat or rice, and by extension, broken grain.
糗 combines 米 (rice/grain) with 臭, which likely contributes the sound and possibly the idea of something dried or processed. The exact historical development is uncertain.
The left side is 米 (rice/grain), and the right side 臭 suggests something that has been altered or processed. Imagine grain that has been parched until it becomes dry and broken, like stale-smelling grain that crumbles.
For キュウ, imagine a cue ball smashing into a pile of parched grain, breaking it further: cue -> キュウ, and the grain shatters.