You just have to try surströmming. It's a delicacy in Sweden. Herring (of course - what else?)
is tinned together with some enzymes to help the fish rot. In time the gasses build up so that the tin bulges outwards. The stench from the fish when the tin is opened is so bad it has to be opened under running water.
The art of eating surströmming is most developed in the far northern areas of Sweden where the dish is said to have originated. It is believed by some that eating surströmming began as a joke, but quickly caught on as way to pass months of monotonous darkness in the winter season. Later, it was determined that eating the delicacy actually warded off many marauding Norsemen, and others bent on conquering the Swedes, including beleaguered Nazis, rampant capitalism, and more recently, tourists. Even Gengis Khan avoided northern Sweden.
Wolfgir informs me I should have a large quantity of strongly flavoured vodka available when I eat it. You can't imagine how sorry I am that I ever uttered the words 'I'll try anything once!'