Green’s Dictionary of Slang

to pull or crush a person’s hat over their eyes, thus temporarily blinding them; also as n.

1892		Daily Tel. 30 Jan. 3/7: A number of roughs [...] made it a practice whilst behind the fence to ‘goffer’ old men as they passed by in the street. Witness, in pantomimic fashion, explained that goffer meant blocking old men’s hats.
1895		Albert Chevalier Record by Himself 141: She thumped his broad back, and gave him a ‘goffer’ – which is costerese for flattening his hat.