AFTER nearly two decades together, WILL SMITH is still trying to turn his street-smart firecracker of a wife, Jada Pinkett Smith, into a more refined lady.

The Hollywood power couple, who met in 1990 when she auditioned for the role of his girlfriend on “The Fresh Prince of Bel-Air,” have even come up with a funny name for their “etiquette lesson game” – My Fair Jada!

“Will is always trying to tone Jada down,” revealed a family insider.

“Jada looks petite and demure, but in a flash she can change into a trash-talking pit bull.”

Jada is said to be particularly tough on people she believes aren’t pulling their weight, so Will went out and bought her an e-book on etiquette and started e-mailing her funny suggestions on how to deal with others without hollering.

“After Jada started yelling at one of their household workers for call­ing her ‘Jada’ instead of ‘madam’ or ‘ma’am,’ Will sent her a little note saying ‘too many cooks spoil the meal – especially when one is a madam!’” revealed the insider.

“Another time, a cleaning guy broke a flower vase, and Jada let him have it with both barrels – ‘clumsy’ is the nicest thing she called him. Will asked her, ‘why you all upset, that was my favorite gravy boat too!’

“Jada wanted to smack Will when he first started making fun of her, but she wound up laugh­ing at his goofy suggestions.”

Will, 44, and Jada, 41, were married in 1997 and have two kids together – son Jaden, 14, and daughter Willow, 12. While they are living a life of luxury, Jada apparently still bears scars from her rough-and-tumble child­hood.

Jada’s mom, Adrienne, got pregnant with the future star while still in high school and ad­mitted to abusing drugs for most of Jada’s young life. Making mat­ters even more difficult, Jada’s father wasn’t around when she was a child – a pain that lingers to this day.

To cope with her rocky upbringing and fre­quent disappointments, sources say Jada developed a hard exterior.

“Taking the rough and tough, unrefined side out of Jada has been a work in progress for Will since they got married,” said the insider. “But it’s a labor of love for him, and now even she likes playing ‘My Fair Jada’!”

POP FYI: fame playwright George Bernard Shaw’s adaptation of the  myth “Pygamlion” was the basis of the musical classic “My Fair Lady”.’