Janky: Of extremely poor or unreliable quality. U.S. slang (chiefly African-American); earliest citations are from the early 1990s. Sometimes intensified as janky-ass or truncated as jank.
Janky was one of a clutch of words added to OxfordDictionaries.com in February 2015. (Other additions included vishing, McTwist, and teachable moment.) The word’s origin is murky; the more comprehensive Oxford English Dictionary says it’s “probably” a regional, affected, or colloquial pronunciation of junky. Juba to Jive: A Dictionary of African-American Slang, published in 1994, classifies it as a noun meaning “bad luck,” and says it’s “probably” a variant of jinxed.