I whistled under my breath as I went to work.

He even began to whistle a tune under his breath.

He tossed the device to V, who whistled under his breath.

He whistled low under his breath, then picked up the sheet to look at more closely.

He whistled under his breath as we shook hands.

Morgan whistled lightly under his breath in surprise as he straightened.

Leon whistled under his breath as he timed the testing.

The other man at the table, when he was not talking, kept whistling aimless little tunes under his breath.

He began whistling under his breath; not a full song, just catches from a tune that had been old when space travel was a dream.

Another uniformed man walked up and down just inside the front door, whistling under his breath.