What does part
If she smokes, she pokes
The "she pokes" part means "she engages in sexual intercourse of a heterosexual variety". There is an implication of doing so more readily or enthusiastically than may be otherwise expected.
You may wish to consult Urban Dictionary on the topic. But then again you may not.
Women smokers were considered to be more promiscuous - mass culture with the advent of the roaring Twenties, but traveling across the Americas prior to that through literature post Civil War (see Elmer Gantry) - which was really an American version of an idea that had been circulating via French Postcards visually.
She smokes, she will have sex
Actually, the phrase should be, "if she smokes, she ALLOWs poking."
If she is "loose" with regard to smoking, she is likely to be "loose" regarding other matters such as sex.
But the original phrase is an abbreviation.
Basically it means if there is no smoke from your exhaust, there will be no poke from your engine!
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