Subbotnik
Subbotnik and voskresnik (from Russian: суббо́та, IPA: [sʊˈbotə] 'Saturday' and воскресе́нье, IPA: [vəskrʲɪˈsʲenʲjɪ] 'Sunday') were days of volunteer unpaid work on weekends after the October Revolution, though the word itself is derived from суббо́та (subbota for Saturday) and the common Russian suffix -ник (-nik). The tradition is continued in modern Russia and some other former Soviet Republics.