For me, the prize definitely goes to that Icelandic delicacy,
hakarl, which is a particular shark meat which has been putrefied for over 4 months. It is worth quoting from the Wikipedia entry:
The shark itself is poisonous when fresh due to a high content of uric acid and trimethylamine oxide, but may be consumed after being processed (see below). It has a particular ammonia smell, similar to many cleaning products. It is often served in cubes on toothpicks. Those new to it will usually gag involuntarily on the first attempt to eat it due to the high ammonia content.[citation needed] First-timers are sometimes advised to pinch their nose while taking the first bite as the smell is much stronger than the taste, which is similar to very pungent Jewish deli-style cured whitefish or herring.[citation needed] It is often eaten with a shot of the local spirit, a type of akvavit, called brennivín. Eating hákarl is often associated with hardiness and strength.
Chef Anthony Bourdain, who has travelled extensively throughout the world sampling local cuisine for his Travel Channel show No Reservations, has described shark þorramatur as "the single worst, most disgusting and terrible tasting thing" he has ever eaten.[citation needed]
Chef Gordon Ramsay challenged journalist James May to sample three "delicacies" (Laotian snake whiskey, bull cough, and hákarl) on The F Word; Ramsay then vomited after eating hákarl, although May kept his down. May's only reaction was "You disappoint me, Ramsay."
As for me, I inhaled from the proffered cube on a toothpick, damn near passed out, and quickly took the merest nibble to say that I had tried it. All to the hilarity of my Reykjavik hosts.
Changing tack for a minute, from delicacies to language, I see on this thread that some contributors have struggled with the plural of cough. Not surprising, really, as one at a time is all most of us generally think about. In any case, the word is Latin, 3rd declension masculine, so the plural is penes. Lest I be accused of being unfairly sexist in passing on this extremely useless erudition, may I also advise you that its opposite number, cough, is 1st declension feminine, and so the correct plural form is coughe. By the way, to the Romans the word referred to the sheath in which their sword was placed.
Keep smiling,
Cocitus23