Green’s Dictionary of Slang

(US) a Jesuit, also attrib.

1930		J. O’Hara ‘Suits Pressed’ in New Yorker 8 Feb. 28/3: He looks like an old French Jesuit I once knew, but the old Jebby didn’t look like a Frenchman.
1931		J. O’Hara ‘Mort and Mary’ in New Yorker 6 June 38/3: He would, of course, be a Jesuit, because wasn’t he going to St. Francis Xavier’s over in Sixteenth Street? That’s a Jebby school.
1946		J.F. Powers ‘Prince of Darkness’ in Accent (Winter) 85: ‘Hopkins has some good things.’ ‘Good—yes, if you like jabberwocky and jebbies! I don’t care for either’.
1947		H. Sylvester Moon Gaffney 60: The Jebbies will give you space in their basement on Eighty-fourth Street.
1965		(con. WWI) D.V. Gallery Eight Bells 27: The Latin, Greek, and ancient history that the Jesuits taught were of no use on those exams. The Jebbies didn’t bear down too hard on Math, and the Navy did [HDAS].
1977		(con. 1949) J.G. Dunne True Confessions (1979) 43: The jebbies wanted the Cardinal’s approval on that new dormitory.