Kalles Kaviar of Sweden:

A salty, fishy-sweet, fleshy-pink (I’m reluctant to say “salmon-colored” here for reasons I trust you understand) paste that one squeezes out of a metal tube, its little eyefuls of fish eggs like gleaming baubles on a reef. Best eaten snaked onto a generously buttered crispbread (chilled potato slices, as shown, are optional, but optimal) with no regard for the imminent halitosis. 

Those stateside or in continental Europe can find it at your local Ikea in the refrigerated snack-fish section. Advanced eaters can expect to finish one tube per week.