A beer jerker is a bartender. You'll associate it, perhaps, with the later soda-jerker.
1881 Baltimore Sun (MD) 4 May 1/3: A Confidence Queen Indicted.— The Richmond [...] grand jury have indicted Bertha Hayman, the accomplished beauty, who has rendered herself so notorious in Canada and elsewhere.
A confidence queen is a "con woman."
1899 Baltimore Sun (MD) 6 Oct. 1/3: 'See her go past her like a shot off a shovel. Wow!'
1922 Baltimore Sun (MD) 15 Aug. 6/6: Brown, superintendant of Hagan's one time force of 'door shakers' (the underworld parlance for special police).