The languages of Japan's Ainu minority and Spain's Basques have similarities that could not be coincidence.
"None of the Ainu words were exactly the same as in Basque, but many were extremely close such as ikoro and koro (money), kokor and gogor (to scold), tasum and eritasun (illness), iska and xiska (to steal). A surprise was the Ainu word nok (testicle) which is much like the Basque word noka (familiarity with women). In English slang the same word is used in "to knock up" meaning "to cause a woman to become pregnant." In Indonesian nok means "unmarried young woman," while dénok means "slender, elegant woman." In Dutch slang the word is slightly altered to neuk (sexual intercourse). There is little doubt that the word goes way back to the Neolithic or even Paleolithic. From the following comparisons it seems clear to me that Ainu and Basque are genetically related."