A sign resembling that of the cross is made on the chin or throat. “You won’t tell?” “No.” “Well, cross your throat.”
Cambridge, Mass.

A sign resembling that of the cross is made on the chin or throat. “You won’t tell?” “No.” “Well, cross your throat.”
Source: Current Superstitions (1896), entry 62.
Fanny D. Bergen, editor.
Modern normalized navigation; the historical attribution above remains unchanged.