Gammon noun the language spoken by Irish Travellers 20-. etymology: origin obscure; first recorded as ‘talk, chatter’ in the late eighteenth century usually in the phrase gammon and patter; at what point in time this came to mean Shelta is unknown note:

Grose and Egan (1823) define Gammon as follows: To humbug, to deceive, to tell lies. What rum gamon the old file pitched to the flat; [how finely the knowing old fellow humbugged the fool].