cut me some slack

[pierrette]

What is the source of "Cut me some slack"?

[Clanad]

Our friends at Word Detective say "...Although we might assume that �slacker� invokes a relatively modern sense of �slack,� the original meaning of �slack� as an adjective in English was, in fact, �lacking in energy or diligence; inclined to be lazy or idle.� �Slack� is based on the Proto-Germanic root word �sleg,� meaning �careless� or �lazy.� �Slack� first appeared in Old English (as �slaec�), meaning �careless in personal conduct,� and that meaning has persisted steadily to this day, when �slacker� is used as a noun synonymous with the old-fashioned �lazybones.�

It wasn�t until the 14th century that �slack� as an adjective took on the meaning of meaning literally �not tight or snug,� and loose trousers weren�t called �slacks� until the early 19th century. �Slack� as a noun meaning �the part which hangs loose, especially of a rope, etc.� (e.g., �Take up the slack in that cord so someone doesn�t trip�) didn�t come into use until the 18th century. But �slack� as a verb meaning �to be remiss; to waste time� dates all the way back to the 16th century

[jno]

presumably it's the idea of a slack rope - 'don't keep me on such a tight leash, slacken it a bit to give me some freedom to do what I want'?

[Quizmonster]

One of the old meanings of 'cut' was to prepare or provide. It was certainly used in this way as long ago as the 17th century, in phrases such as 'Cut him some work to do.' Americans still use it in this way when they speak of 'cutting' a cheque.
As already suggested above, the 'slack' element probably refers to rope, as if the speaker was on some sort of leash. Thus. "Provide a longer leash so that I have more freedom of action!"