H.L. Mencken (18801956). The American Language. 1921.
into English, had a revival during the early days of David Lloyd Georges career, was adopted into American without any comprehension of either its first or its latest significance, and enjoyed the brief popularity of a year.
Krapp attempts to distinguish between slang and sound idiom by setting up the doctrine that the former is more expressive than the situation demands. It is, he says, a kind of hyperesthesia in the use of language. To laugh in your sleeve is idiom because it arises out of a natural situation; it is a metaphor derived from the picture of one raising his sleeve to his face to hide a smile, a metaphor which arose naturally enough in early periods when sleeves were long and flowing; but to talk through your hat is slang, not only because it is new, but also because it is a grotesque exaggeration of the truth.12 The theory, unluckily, is combated by many plain facts. To hand it to him, to get away with it and even to hand him a lemon are certainly not metaphors that transcend the practicable and probable, and yet all are undoubtedly slang. On the other hand, there is palpable exaggeration in such phrases as he is not worth the powder it would take to kill him, in such adjectives as break-bone (fever), and in such compounds as fire-eater, and yet it would be absurd to dismiss them as slang. Between block-head and bone-head there is little to choose, but the former is sound English, whereas the latter is American slang. So with many familiar similes, e. g., like greased lightning, as scarce as hens teeth; they are grotesque hyperboles, but surely not slang.
The true distinction between slang and more seemly idiom, in so far as any distinction exists at all, is that indicated by Whitney. Slang originates in an effort, always by ingenious individuals, to make the language more vivid and expressive. When in the form of single words it may appear as new metaphors, e. g., bird and peach; as back formations, e. g., beaut and flu; as composition-forms, e. g., whatdyecallem and attaboy; as picturesque compounds, e. g., booze-foundry; as onomatopes, e. g., biff and zowie; or in any other of the shapes that new terms take. If, by the chances that condition language-making, it acquires a special and limited meaning, not served by any existing locution, it enters into sound idiom