"Whenever flotsam and jetsam meet for a drink they always reminisce about the family's long-lost triplet - lagan. That's the word for goods or wreckage that lie at the bottom of the sea and, like Gummo and Zeppo Marx, it rarely gets a mention".
"There's a simple mnemonic that helps distinguish flotsam from jetsam. Flotsam (or floatsome) are those items which are floating as a consequence of the action of the sea. Jetsam are those which have been jettisoned by a ship's crew (although that may float too of course). "
Live and learn!

Полностью: www.phrases.org.uk/meanings/flotsam-and-jetsam....