This phrase stems from cotton fields that were tended by slaves.

Pick my cotton in other words means 'do me a favor' but is not a question, it has more of a 'do it' tone.

Usually the favor being asked is a simple physical favor such as turning off a light or plugging in cables.

Alternatively it can be used as 'I'll pick your cotton' which is used to say, 'Yes I will do you a favor, but I hate you.'
"Dude can you pick my cotton here?" Pointing at the TV and PS3.
"Fine..."

"Grab my coffee while you're in the kitchen."
"Fine, I'll pick your cotton. Bastard."
by Ogen July 20, 2009
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