Snickerers and snorters keep their mouths closed, titterers and grunters pulse through parted teeth, wailers and barkers yawp through gaping mouths and throats.

He was a small thin man, this titterer, with too-bright eyes, vaguely purple skin, and a well-greased shock of stiff green hair.

And the presence of one Cockney titterer will cause a whole party to walk in clouds of darkness.