The online OED has an interesting etymology of monkey-business:

colloq. (orig. U.S.).
[< MONKEY n. + BUSINESS n., probably after Bengali bā̃drāmi. Compare modern Sanskrit vānara-karman (< vānara monkey + karman action, work, employment), Hindi vānara-karma.] 

Bengali বাঁদর bāndara is “monkey” and বাঁদরামি bāndarāmi is “mischievousness; a monkey-trick; monkeyism”. But it seems strange that monkey-business, a US usage, would be a calque from an Indian language. None of the citations give any clue why this might be.

1858 T. P. THOMPSON Audi Alteram Partem I. lxv. 249 The Native Indian term for the supreme of folly, is ‘monkey business’.

1883 G. W. PECK Peck’s Bad Boy 109 There must be no monkey business going on.

1934 C. DAY LEWIS Hope for Poetry vi. 29 A pandemonium of slogans, national anthems, headlines..manifestos, monkey business.

1972 ‘H. CARMICHAEL’ Naked to Grave vi. 79 Because I’ve seen her talking with one of the neighbours isn’t to say there was any monkey-business between them.

1996 Sugar June 112/2 If you’re up to monkey business, be extra cautiousyou could get caught out.

It is worth noting that, despite the “orig. U.S.” comment, the first citation is from a British writer (Googlebooks reveals that the cited source is a compilation of letters by Major General Thomas Perronet Thompson, M.P. for Bradford, to his constituents). I cannot but suspect that it came into US English via UK English, and is a legacy of British imperial rule of India.

Edit: Also at Googlebooks, I found “monkey business” used by Thompson in an 1837 letter in a compilation called “Exercises, Politcal and Others” published in 1843.

OK, so “Native Indian” in that quote means “south asian”.

We shouldn’t be surprised to find that more than one culture equates monkeys with mischief.

I’m not surprised about that, I was suprised that the phrase “monkey business” was a calque, and a calque from Bengali when it’s an American usage - altho now that we know the first quote is British it makes more sense.

The comparison of persons or actions to simians must have predated British colonialism. Shakespeare had the term jackanapes, supposedly from Jack Napis, nickname of William de la Pole, Fourth Earl and First Duke of Suffolk (1396-1450). OED1 says origin uncertain, but the word certainly referred to apes and apelike behavior.

Here’s Word Detective on it: Evidently de la Pole’s family had also made an unfortunate choice in their coat of arms, which boasted a collar and chain of the sort most often, at that time, seen tethering pet monkeys.  Pet apes or monkeys were, in those days, known as “Jack Napes,” the “Jack” possibly because it was a common name applied to both animals and people (e.g., “jackass,” “Jack Tar,” a sailor).  “Nape” might simply be a play on “ape,” or possibly reflects the fact that many pet apes were shipped to England via Naples.

It seems reasonable to assume that the term was around before the Earl, at least by a bit. The leap to monkey business wouldn’t have necessarily involved any awareness, other than by a soldier or two, that the usage existed in a foreign language.

edit: I agree it would have been mysterious if the term were American, deriving from Bengali.

jointgib - 20 June 2009 05:32 AM

We shouldn’t be surprised to find that more than one culture equates monkeys with mischief.

I would be a bit surprised if North American Indians did since there are no native monkeys north of Central America.

I don’t know what went on the OED’s editorial process when this entry was updated, but I suspect that the “orig. U.S.” is a mistaken holdover from the old entry. The 2nd Edition (1989) version has “orig. US” and the first citation as the 1883 Peck quote (which is American)—and there is no Bengali etymology. When they updated the entry for the 3rd Edition in June 2008, they added the 1858 Thompson quote and the Bengali etymology, but retained the “orig. U.S.” note. I don’t know whether this is an error, or if they did not consider the Thompson use of the phrase (which is in quotes) to be a fully Anglicized usage.

Myridon - 20 June 2009 09:54 AM

jointgib - 20 June 2009 05:32 AM

We shouldn’t be surprised to find that more than one culture equates monkeys with mischief.

I would be a bit surprised if North American Indians did since there are no native monkeys north of Central America.

Are we discussing North Amercian Indians?

goofy - 20 June 2009 09:12 AM

I’m not surprised about that, I was suprised that the phrase “monkey business” was a calque, and a calque from Bengali when it’s an American usage - altho now that we know the first quote is British it makes more sense.

Yes, sorry, i see what you’re saying now.

jointgib - 20 June 2009 12:49 PM

Are we discussing North Amercian Indians?

Are there some kind of Indians outside of south Asian and American?  It seems unlikely that T. P. Thompson would say “Native Indians” if he meant only Central and South American Indians at least not without being clearer.

I am truly surprised to learn that bandrami in Bengali has metamorphosed into monkey business. Being a native Asian, south Asian and a Bengali-speaking native from India at that, I can vouch that bandrami connotes different shades of mischievousness that are not conveyed by monkey business. (a) Children are often accused of bandrami when they climb trees or tall structures dangerously, or tease a mate with unseemly gestures, or do several naughty things that no self-respecting monkey ever does; (b) adults commit bandrami when they do mischievous things not befitting their age; (c) when a male of the species homo sapiens sapiens tries to draw the attention of a female with unbecoming gestures. There are other shades of that ilk. (a) and (b) have mischievousness in common; and (a) and (c) share monkey-like gestures and postures as seen by a detached observer. That much fall legitimately within the monkey business ambit. The other shades of the Bengali meaning can only be understood when one considers that bandar itself is a swear word: it means (1) ugly, (2) irreverent, (3) mischievous, (4) clannish and (5) someone with aggressive posture.
The Bengali tongue is full of contradictions ill-understood by others. Elderly Bengalis often use the word bandar lovingly to refer to youngsters whom they like.

Yup, it’s one of a number of Indian words brought into English by the British occupation. Welcome aboard.

Yes indeed: welcome aboard, Aniruddha Sen!

I don’t think it’s very surprising that the meaning of the metaphor monkey business was rapidly modified once it was adopted into English from Bengali. This very often happens when metaphors from one culture is adopted by another, especially when the adopting culture has a different experience – or none - of the phenomena on which the metaphor is based.  The vast majority of English-speaking people have no experience of monkeys other than behind the bars of zoos, or latterly in wildlife documentaries; so it’s natural that our idea of them, and the way we use them in metaphors, should be different from that of Bengalis who live alongside them.

I don’t think that referring affectionately to a youngster by an epithet normally considered insulting is hard for people of other cultures to understand. English-speaking parents quite readily call a loved child a “little devil”, or “monster”, or “tyke” (the last of which means “dog of no breeding or value”), and Yiddish-speaking grandparents would use momzer (bastard) or bonditt (crook) as an endearment.