Green’s Dictionary of Slang

a euph. for O Christ!

1909

J. Ware Passing Eng. of the Victorian Era 185/1: O! cry! (Peoples’). Exclamation, of satiric surprise, confounded with cry, but probably nothing to do with it. ‘O! crickey!’ may be another shape of the expression. May be an evasion of ‘O! Christ!’.