Sentence:  As I reluctantly left Tangkoko for the last time, bumping along the trail on a motorbike, Raoul, the alpha male who had smacked my leg, wandered out from among the trees. He was alone, and after I <WSD>puttered</WSD> by, I glanced back to see him swagger into the middle of the path to watch me go. 
Meaning of the word marked with <WSD> tags:  To produce intermittent bursts of sound in the course of operating.