Your spouse's brother's/sister's spouse. Basically someone who will never be related to your kids, so you don't have to give a shit about. The feeling is mutual.
Synonyms for In-law in-law
On this page, you will find 30 slang terms related to in-laws. Some of the top words include: philipson, wittol, kin, safak, small penis, and 25 more.