Literally "white children", shirako is a Japanese
euphemism for soft roe, which in turn is an euphemism for
milt, which is a technical term for fish sperm.
It's white, it's globby, it's gooey,
it looks exactly like you'd expect fish sperm to look and
it tastes worse: "even my own tastes better",
to quote a friend. Shirako is most often spotted in
kaitenzushi restaurants, where it is plopped into a little boat of
rice and nori to await the unsuspecting gaijin.