The Collaborative International Dictionary
Halter-sack
Halter-sack \Hal"ter-sack`\ (h[add]l"t[~e]r*s[a^]k`), n.
A term of reproach, implying that one is fit to be hanged.
[Obs.]
--Beau. & Fl.
Wiktionary
halter-sack
n. (context obsolete derogatory English) One who is fit to be hanged; a scoundrel.