"Gunk" is the poor makeshift that must be employed to indicate it.
Penrod uttered one half-hearted "Gunk" as he turned in at his own gate.
However, this stimulated him, and he paused to practice.

"Gunk!" he croaked.

"Gunk-gunk-gunk-gunk!" Mrs.Schofield leaned out of an open window upstairs.
"Don't do that, Penrod," she said anxiously.

"Please don't do that." "Why not ?" Penrod asked, and, feeling encouraged by his progress in the new art, he continued: "Gunk--gunk-gunk! Gunk-gunk--" "Please try not to do it," she urged pleadingly.

"You CAN stop it if you try.