'brass,' 'cheek,' etc, the reverse of the shield is given. Such reversals in the legitimate meanings of words are not uncommon in slang.
Bam, subs. (old slang).—1. A cheat; an imposition; a story intended to hoax the credulous; what nowadays generally goes under the name of chaff or humbug [bam is thought to be an abbreviated form of bamboozle (q.v.)]. Murray has traced it back to 1762, but it appears nearly twenty years previous in Dyche's dictionary, and also in Martin's, the second edition of which was published in 1754.—See verb To bam.
1748. T. Dyche, Dictionary (5 ed.). Bam (s.), a sham or pretence, a lying excuse.
1762. Foote, Orators, Act ii. Why I know that man, he is all upon his fun; he lecture—why 'tis all but a bam.
1817. Scott, Rob Roy, ch. ix. 'It's all a bam, ma'am—all a bamboozle and a bite, that affair of his illness.'
Verb.—To hoax, to bamboozle; to wheedle; to cheat. [Of same formation as substantive, which see above, and Cf., Bamboozle.] The first trace of it appears in Cibber's Double Gallant [1707], and is discussed by Swift in his introduction to Polite Conversation [1738], where he mentions among 'the exquisite refinements' then in vogue,—bam for bamboozle, and bamboozle for, God knows what. Whereupon a correspondent of Notes and Queries [2 S., Jan. 10, '57, p. 31] alluding to the despair of etymologists in regard to these words remarked that if from was put in the place of for, it would describe the predicament in which philologists are placed.
1754. H. Martin, Eng. Dict., 2 ed. To bam, or to bamboozle, to fun, to fib, to sham.
1760. Colman, Polly Honeycombe, in wks. (1777) IV., 43. Lord, how well he behaves! We shall certainly bam the old gentleman.
1830. Marryat, King's Own, ch. xlix. 'Now, you're bamming me—don't attempt to put such stories off on your old granny.'
1874. E. L. Linton, Patricia Kemball, ch. xxxix. For a moment the thought flashed across him whether 'that tale of Gordon Frere was all a bam, and had the girl taken a liking for himself?'
Bamblustercate, verb. (nonce-word).—A factitious creation signifying to embarrass; confuse; or hoax in a blustering manner. [From bam, to hoax, or confuse + bluster, noisy assertion + cate, a termination in imitation of 'conglomerate'.]—See also Comflogisticate.
Bamboo, verb. (American).—A corruption of bamboozle. To cheat; to victimize; to hoax.—See, however, Bam and Bamboozle.
Bamboozle, verb. (familiar).—To hoax; deceive; or impose upon. Philologists are all confessedly at sea in regard to the derivation of bamboozle and its attributive forms, but the general tendency of evidence is to refer it to a gypsy origin. Johnson states it to be a cant word; and Bouchier, in his glossary says, 'it has with great propriety long had a place in the gypsy or canting dictionaries,' it being in his opinion 'the sole invention of gypsies or vagrants.' Leland thinks it 'possibly' the Hindu word bambhorna, to humbug, with the gypsy terminative
