A Wordorigins post quoted the online OED’s etymology of monkey-business:
[< MONKEY n. + BUSINESS n., probably after Bengali bā̃drāmi. Compare modern Sanskrit vānara-karman (< vānara monkey + karman action, work, employment), Hindi vānara-karma.]
This is interesting enough on its own, but what leads me to post about it is this extremely informative comment from Aniruddha Sen:
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.
Mr. Sen then made a separate post to discuss his theory that “the commonest pan-Indian swear-word” s(h)ala, literally ‘brother-in-law’ (from Sanskrit shyalaka), which “became a swear-word perhaps because of the I-sleep-with-your-sister connotation,” is actually a borrowing from Insha’llah, since according to his research “the swear-word starts appearing about a century after Islamic occupation”; sounds dubious to me, but I thought I’d put it out there for comment.