(cliché)   Fig.: to not know someone at all. It refers to someone completely unknown to whoever is using the term.

Who the hell is this James who claims to be an old friend of mine? I don't know him from Adam!

Ma chi diavolo è questo Giacomo che dice di essere un mio vecchio amico? Io non l'ho mai visto né conosciuto!

"Who was that guy over there looking you up and down?" "I don't know honey. I swear I don't know him from Adam!"

"Chi era quel bellimbusto che ti faceva gli occhi dolci?" "Non lo so amore mio! Ti giuro che non l'ho mai visto né conosciuto!"

The origin of this expression is uncertain, but it may have come from an old argument over whether Adam and Eve had navels. Many famous paintings show them with a navel, but it has been argued that they couldn't have one. In 1944 a number of Sherlock Holmes' admirers wrote "Profile by Gaslight", a series of episodes about the detective private life. Dr. Logan Glendenning wrote about a case that Holmes solved after his death. He was called upon in heaven to locate Adam and Eve, who had been missing for a long time and nobody could find. Holmes recognized them quite easily, for he alone - among all the searchers - knew the others from Adam: only Adam and Eve had no navels!