Green’s Dictionary of Slang

1. (UK Und.) a large, silver pocket watch.

1845		J. Lindridge Sixteen-String Jack 392: You have a watch or so, for which I must trouble you, come madam, that frying pan.
1858		‘A. Pendragon’ Queen of the South 35: Mr. Sol Lazarus, as the old-fashioned watch [...] was handed to him, affected to look very disdainfully at it, muttering ‘Frying-pan’.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor IV 321/1: It was a silver watch, which we called a ‘Frying Pan’.
1866		Wild Boys of London I 238/1: Twenty times [...] did Tommy consult his frying-pan.

2. (US) a banjo.

1863

Criminal Life (NY) 19 Dec. n.p.: Joe D—s thinks he is ‘some’ on the banjo. He has been getting his ‘frying pan’ silver-plated.