sour, v.¹ — Green’s Dictionary of Slang

sour v.¹

[? SE sour, to cause fermentation]

(UK Und.) to beat.

1725		New Canting Dict. n.p.: sowr to beat violently, &c. As, Sowr the Cull; i.e. Knock him down: Beat him without Mercy.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. 1725].