Euphemism for a female masturbating.
It is derived from the shape of the American state of
Oklahoma and its resemblance to a
hand with a protruding
finger that can be used to stimulate the vaginal cavity.
"Well,
Johnny canceled our date to go take care of his
sick mom," Elizabeth complained.
"That
asshole!" her friend Jayden exclaimed.
"I was fucking horny too," Elizabeth replied.
"You can always take Mister Oklahoma out tonight."