Definition of "guffin"

I used to swallow all that stuff, but I'm not such a guffin now.

1885, George Manville Fenn, Bunyip Land

“You must have been a silly little guffin,” said Sinclair.

1912, R. Austin Freeman, A Woman's Vengeance

She did not like Archibald. She said she liked big, manly men. Behind his back she not infrequently referred to him as a 'gaby'; sometimes even as that 'guffin'.

1914, P. W. Wodehouse, The Man Upstairs and Other Stories, Archibald's Benefit