To harp upon; to dwell upon a subject. Have among you, my blind harpers; an expression used in throwing or shooting at random among the crowd. Harp is also the Irish expression for woman, or tail, used in tossing up in Ireland: from Hibernia, being represented with a harp on the reverse of the copper coins of that country; for which it is, in hoisting the copper, i.e. tossing up, sometimes likewise called music.
HARP
Meaning of HARP in English
Slang English vocab. Английский сленговый словарь. 2012