The Long and Short of It
From The Consumerist:
Coca-Cola has a new adult beverage that’s a blend of “unique Coke refreshment with the true essence of coffee and has a rich smooth texture and has a coffee-like froth when poured.” Coca-Cola Blāk will launched in France, because if you consume cold snails, you will consume anything.
The macron over Blāk was specially designed by Coca-Cola scientists to help onomatopoeize the sound you’ll make after drinking the concoction.
Well, a macron it is, as you can see from the image above. The trouble is, of course, that a macron--from the Greek "makros", "large" or "long", as seen in the English prefix "macro-", as in "macrobiology"--is a mark used in English to denote a long vowel sound, meaning that "Blāk" isn't pronounced "black", but "blake". (Long and short vowels in English aren't necessarily distinguished by their length: the long vowels in "mate", "mete", "might", "moat", and "mute" needn't be any greater in duration than those in "pat", "pet", "pit", "pot", and "put". The real difference between long and short vowels in English is that long vowels are, for lack of a better term, higher-energy vowels: they take more muscle power to say.)
What the marketers surely wanted for their product name was a breve, which, as the name clearly suggests (it's the second syllable in "abbreviate" or the first in "brevity", your choice), denotes a short sound: "Blăk", which is to say "black". (Neither diacritical mark produces the sound that The Consumerist seems to be alluding to, "blech".)