There are all sorts of silent letters tiptoeing around the English language. There's the P in pterodactyl, the G in gnaw, and, when Jean Harlow pronounced the T in Margot Asquith's first name, Mrs Asquith corrected her by saying that "The T is silent, as in Harlow."
There are a bunch of silent Bs in the middle of words like debt and lamb, but rarely, oh so rarely do you find one at the beginning of a word. But over at the ever-enchanting Six Degrees of Sir Thomas Urquhart, there is one. And it's rather useful. The word is bdelygmia, which means a long series of insults. So when you say to a chap that he's a bounder, a rogue, a scoundrel, a scallywag and a dog-fondler, that's bdelygmia, which a silent B.
Or as Shakespeare put it:
A knave, a rascal, an eater of broken meats; a base, proud, shallow, beggarly, three-suited, hundred-pound, filthy, worsted-stocking knave; a lily-livered, action-taking knave; a whoreson, glass-gazing, super-serviceable finical rogue; one-trunk-inheriting slave; one that wouldst be a bawd in way of good service; and art nothing but the composition of a knave, beggar, coward, pander, and the son and heir of a mongrel bitch; one whom I will beat into clamorous whining if thou deniest the least syllable of thy addition.
For those interested in the silence of the second letter, The Oxford English Dictionary also has:
Bdellatomy - The name given to the practice of cutting leeches to empty them of blood while they still continue to suck.
Bdellium - The name given to several trees or shrubs of the family Amyridaceæ, chiefly of the genus Balsamodendron, from which exudes a kind of gum-resin resembling impure myrrh, of pungent taste and agreeable odour, used in medicine and as a perfume.
Bdellometer - A surgical instrument proposed as a substitute for leeches, and fitted to show the amount of blood drawn.
I remember being shown this video as school when I was about seven. It was my first introduction to Tom Lehrer.