coincidence, (or if said under one's breath)... a Suspiciously Unusual Coincidence.

Street slang by barely literate Irish, Jewish, German, Italian and Chinese street toughs (such as the Pug Uglies , Black Hand, Purple Gang and Tong Hatchet Men) from NY's ethnic ghettos of the 19th Century, specifically, the Lower East Side, Five Points, China Town (Manhattan), and Flatbush, Empire, Coney Island (Brooklyn)... later evolved into nationally used street slang by early 30s talkie gangster /prison movies and then into the common vernacular by such comedians as The Three Stooges' and 'The Marx Brothers'.