Attpåklatt and other untranslatable people-based Norwegian

I've seen "Attpåklatt" to mean a sibling born 7-10 years later, and the word to translate directly as 'afterthought', or maybe even 'after blob'.

It's such a rich word, and I've been cautioned not to put any more meaning on it than the above i.e. it's not necessarily an unexpected or bad thing, what other anthropological or nature-based words have you enjoyed translating in your travels between English and Norwegian?