A Moll was a girlfriend or woman companion so im guessing a slack moll would be a slack girlfriend/woman companion, probably sexist saying the woman was not doing the job properly or meeting the man's expectations.
Slack as in "lacking firmness" is an adjective. Slack as in the action "to slack" is a verb. Slack is also used as a noun to describe a part of a rope or a bog. A verb is a word that describes either an action (walk, run, etc), an occurrence (become, happen, etc) or state of being (stand, exist, etc).
Both limp and slack can refer to lacking tightness or firmness. However, limp typically describes a lack of strength or vitality in something that should be firm or rigid, while slack often refers to something that is loose or hanging with excess material.
-to release the pressure or tension on something. e.g. You're gonna slack up on that rope, u tied the girl with, right now!
Loose or slack; not tense It is from Old and Middle English
It's a topographical surname from England, meaning "shallow valley."
Randy Moll's birth name is Moll, Randall.
Biel Moll's birth name is Gabriel Moll Blanes.
Natasha Moll's birth name is Natasha Moll Padrn.
Richard Moll's birth name is Charles Richard Moll.
Roberto Moll's birth name is Roberto Moll Crdenas.
Marg Moll died in 1977.
Marg Moll was born in 1884.
Moll Dyer died in 1697.
Moll Pitcher was born in 1736.
Moll's Mobil was created in 1967.
Moll's Mobil ended in 1971.
Guy Moll was born in 1910.