It's no great surprise to find words in another language that have no English equivalent, if what they refer to is an object that's unfamiliar to most English speakers. For example, it's scarcely surprising if English has no word for "dates that aren't quite ripe yet, but that already ooze honey if you bruise them" (Kwarandzyey azMamweg); only a very small number of English speakers are familiar with date maturation stages, whereas practically all Belbalis are. It's a bit more interesting when you find that a phenomenon equally common in both cultures can be described by a fixed word or phrase only in one of them. Here's a case in point that came up in my latest fieldwork.
One of the basic states of mind in Kwarandzyey (and among the few to be retained from Songhay) is being heLLo. Songhay cognates (from *hollo) mean "crazy, possessed", which in Kwarandzyey is bA; the Kwarandzyey meaning of heLLo is quite different. This word is used (usually with a smirk) of people acting happy (leaping around, singing, dancing, etc.) or showing inordinate confidence, with no thought for consequences or respectability - Har ndza ghar ana hell-a bA ddzunets ka, "as if he was the only person in the world". Being full, or intoxicated, helps make people heLLo, but isn't essential. A heLLo person is generally said not to praise his Lord (asbayHemd an mulana si), ie not to appreciate that the causes of his happiness are contingent. Arabic translations suggested include colloquial SameT (literally "bad-tasting", but as a mental state more like "inconsiderate" or "silly") and classical Taaghii (as in "Nay, but verily man is rebellious (yaTghaa) That he thinketh himself independent!"). Here's a nice example of people acting heLLo (apologies to football fans - the example I was looking for was South Africans celebrating in the streets after Mandela's release, video of which was described to me as showing people being heLLo, but I couldn't find it):
Obviously, the mental state is at least as present in English speaking cultures as in Tabelbala - in fact, it might be reasonable to say that regularly achieving heLLo-ness is an important and widely socially accepted goal for British youth. But is there a word or fixed phrase corresponding to the concept in English? If you can think of one, feel free to suggest it!
(PS: Pardon the transcription - my computer is broken, and I can't be bothered to do all the cut-and-pasting it would take to fix the diacritics.)