Whispering Jack

Etymology
Most famously associated with singer Whispering Jack Smith (1898-1950), but in earlier use as a nickname.

Proper noun

 * 1)  A person who vocalizes quietly, in a whispering manner, or, ironically, one who is loud and outspoken.
 * 2) * 1879 Jan., "A Night with Burglars" in Gleason's Monthly Companion, vol. 8, no. 1, p. 281 (Google preview):
 * The two who sat at a table in an obscure corner of the room were the noted burglars "Whispering Jack" and "Jim the Cracksman," as they were nick-named by their associates.