on the nail

Allegedly from the tradition of striking bargains by placing cash on the nails in Bristol, Limerick and Liverpool. The Oxford English Dictionary, however, cites an Anglo-Norman phrase from c. 1360, "payer sur le ungle" to pay on the (finger)nail meaning "to pay immediately and in full", and the Latin "ad unguem", exactly. It quotes parallel usages from 17th century French, Dutch and German sources and adds that "N.E.D. (1906) notes that: ‘the explanations associating it with certain pillars at the Exchange of Limerick or Bristol are too late to be of any authority in deciding the question’."

on the nail

1. (British) immediately, without delay
   • 1596, Thomas Nashe, Have With You To Saffron Walden:

     Tell me, have you a mind to anything in the Doctor's book? Speak the word, and I will help you to it upon the nail.

   • 1845, Benjamin Disraeli, Sybil, Or, The Two Nations:

     You shall have ten thousand pounds on the nail, and I will take you back to London with me besides and teach you what is fortune.

• anthelion