Schwippschwager

Etymology
Probably from regional 🇰🇲, thus “wry, deviating, indirect brother-in-law”. For the verb compare. Alternatively a reduplicative ablaut derivation like, , etc., but the -pp- is more readily explained by the first-mentioned theory.

Noun

 * 1) co-brother-in-law
 * 2) the husband of someone's spouse's sister;  those married to a group of siblings in relation to each other
 * 3) the brother of someone's sibling's spouse;  the siblings of a married couple in relation to each other