↑ Brian Joseph argues that Yiddish lacks a comparable idiom, that German communities in America in Pennsylvania and Texas lack a comparable idiom, that Americans were unlikely to borrow from standard German in the post-WWI, mid-WWII era, and that German es (’s) is unaccounted for in any case. He says: "[It may be] an inherited anomaly from earlier stages of Germanic, persisting into Modern English. This possibility is enhanced further by the fact that a cognate to the Germanic *geb- 'give' root is found in Latin habeo: 'have', which itself figures in an (admittedly late) existential construction with an impersonal form of the verb (3SG habet)."
Etymology
First attested in 1940. in John O'Hara's 1940 novel Pal Joey. The term is considered by the American Heritage Dictionary of Idioms, Second Edition (2013) and several other references to be a calque of Germanwas gibt's? and/or a Yiddish equivalent. Brian Joseph considers this unlikely, however, and speculates that despite its extremely late attestation, it and the German was gibt's may "allow[] for a reconstruction of a Proto-West-Germanic existential use of 'give', which survives marginally into present usage."[1]