Simulated sound of a guitar, or whatever instrument Edwin chooses to play. The OED (229), in its characteristic style, pins it down thus: “Tink: A representation of the abrupt sound made by striking resonant metal with something hard and light. Often reduplicated in imitation of the repetition of such a sound, also with such variations as tink-tank, tink-a-tink, etc.” Kravetz (181) opines that tink-a-tank is too clumsy a sound for a guitar, more like a banjo. Green (145) would seem to agree. Knight, however, votes for a mandolin (178). One cannot be too meticulous in vital matters such as these.