He tapped twice on the back of his head.

The cop nodded to himself and tapped twice on the roof.

The guard turned left, paused outside a door and tapped twice.

Something, soft as a large leaf, tapped twice against his ear.

He tapped twice on the panel which shut them off from the aide.

Alone in his room, Jerwyn tapped twice upon the door.

He even once or twice tapped his boot toe in time to the music.

Jan tapped twice on her notebook and studied the screen.

Leaning over the lighted box, he tapped twice upon the lid.

He leaned forward and tapped twice on the glass that separated him from the driver.