Green’s Dictionary of Slang

(S.Afr./UK prison) to trick, to hoax, to dupe; thus gesseiner, valuables, belongings.

1950		P. Tempest Lag’s Lex. 94: gessein [...] To ‘con’.
1959		J. Yates-Benyon Weak and the Wicked 120: If a merchant sailor complained that he did not like his ship because ‘she’s a bloody two-stacked gesseiner,’ [...] I knew that in his opinion, his ship is a two-funnelled garbage-can.