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Verb: Rhyming slang for male masturbation. To "have a pull". When friends and accomplices are used to the term, it can be shortened to a "cotton" for public discretion.
Eg 1: Jimmy was so worked up after a boys night out at the strippers, he went home immediately to have a cotton wool.

Eg 2: Q "Where's Steven?"
A "He's out the back having a cotton"
by Paulie Boy June 27, 2006