Early 20th century; earliest use found in Lines. Origin uncertain. Perhaps from Urdu and Indo-Persian †ḥujjat kāfī fīhi, lit. ‘the argument is sufficient’, there's no more to be said about it (from ḥujjat + kāfī sufficient (from Arabic kāfī sufficient) + fīhi in it, about it), probably reinterpreted in colloquial South Asian pronunciation. Compare modern Persian ḥujjat kāfī that's all there is to it.