Dr. Phil's Son Sued -- You Told Me Your Dad was a Marketing GOD

Dr. Phil's son wants to be the next KING in the world of female bodybuilding ... with a little help from daddy ... this according to a new lawsuit.

Phil's kid -- Jay McGraw -- is being sued by a hot blonde fitness instructor named Holly Holton ... who claims she created a gym program geared towards women called Pink Iron.

It's kinda cute ... her L.A. gym has pink weights with hearts on the barbells.

But we digress ... point is, Holly claims Jay approached her and wanted to license her brand for next to nothing ... in exchange for a TON of publicity from his world famous father.

According to the suit, filed in L.A., Holly claims Jay promised, "My dad will market the sh*t out of Pink Iron."

Holly claims she agreed to the deal ... and was all set to become the spokesperson for the product ... but Jay backed out and partnered with a different company, which is named P.I.N.K. Method.

To make matters worse, Holly claims the spokeswoman for P.I.N.K. Method bears a "striking similar resemblance" to herself ... blonde, hot and toned.

Holly is suing for breach of contract ... and wants a ton of cash to make things right, though she doesn't specify an amount.