Green’s Dictionary of Slang

Joe n.¹

In exclamations

by Joe!

(US) a mild oath; euph. for by Jesus!

1846		in Utah Historical Quarterly V (1932) 100: By Joe, it is rich [HDAS].
1862		in Manuscripts XXX (1978) 17: There by joe said the yankey [HDAS].
1865		W. Hilleary diary 12 Apr. in Webfoot Volunteer (1965) 55: But they pulled up stakes, they did, by Joe.
1899		F.E. Daniel Recollections of a Rebel Surgeon 27: Bill threw himself down behind a great big old sycamore, and, by Jo, right plump into a bumble bee’s nest! [Ibid.] 194: Aneurism, by Jo! Man’s dead!