That noise The Nipper makes when a skateboard, helicopter, truck, spaceship, boat, or other transportative device is going a particular speed through a particular environment.
It is often accompanied by the noise he makes for rapid-fire machine guns.
And is sometimes followed by the death throes and screaming, lashing about from the passengers/enemies/passers-by.
The long, long, long, long and involved explanation of what is *actually* happening, *actually*, since he is not permitted to play with guns. Those noises are *actually* lasers, not *actually* rapid-fire machine guns or howitzers.
The Nipper’s rosebud mouth and very precise articulate speech, and the tender hugs and kisses he offers as recompense for breaking the ‘no guns’ rule.