がまのあぶら

がまのあぶら【蝦蟇の膏】

〔むかし香具師(_やし)が口上を述べて売った軟膏〕 an ointment made from toad secretions mixed with pork grease, etc.; toad-oil ointment; “snake oil”.

ガマのあぶら売り a street vendor of toad-oil ointment (in premodern Japan).