According to the search results, "Eskimo sisters" is a slang term that refers to two women who have had sex with the same man on different occasions. The term "Eskimo" is considered offensive by some, and it may have originated from a custom in Alaska of "reciprocal spouse exchange, sometimes described as co-marriage". The term "Eskimo brothers" is also used to describe two men who have had sex with the same woman. While some people may view becoming Eskimo siblings as a special type of bond, others may find the term offensive or inappropriate.