Green’s Dictionary of Slang

busk v.

also busk it
[? naut. jargon busk, to cruise the seas, esp. as a pirate; ult. Ital. buscare, to filch, to prowl]

1. [mid-19C] to sell obscene songs and books in the streets and public houses; thus busking n.

2. [mid-19C] to sell goods to a retailer; thus on the busk.

3. [mid-19C+] to work as a street performer; thus busking n.