HMG – When Cameron Diaz and her ex, Justin Timberlake ran into each other on the set of the ‘Hope for Haiti’ telethon in January, it didn’t either long to remember why they once were an item.

“Cami had forgotten what fantastic chemistry she had with Justin.” says one insider.

But Justin’s now connected to Jessica Biel, which meant Cameron’s overtures fell on deaf ears. But she was not deterred. Now shooting her new comedy ‘Terrible Teacher’ for Columbia, Cameron, 37, insisted Justin be cast as a male lead, instead of people like Ryan Reynolds and Bradley Cooper, whom the studio wanted.

“Cameron kept telling them she wanted Justin,” the source tells OK. “She was bummed because the studio said they didn’t reckon Justin would be excellent on the huge screen.”

But the sweet San Diegan just would not give up;

“Cameron really pushed it,” says the snitch. She played the Columbia suits a few clips from Justin’s new comedy ‘The Social Network,’ which tells the tale of, and according to the source, “that sold them.”

“Terrible Teacher’ involves some mild like scenes between Cam and her co-star, and this was clearly her motive;

“Cameron made them rewrite the like scenes,” the source reveals. “She doesn’t want to stir up distress – she’s been cheated on; Justin cheated on her. She just didn’t want to hurt Jessica.”

Jessica, meanwhile, was said to be ‘freaking out’ about her boyfriend’s new coworker, but then she and Cameron talked on the phone and it’s cool.

“Jessica said she was thrilled he was working with someone of Cameron’s caliber and thanked her for going to bat for him,” so we’re told.

And so ends this tale….the original of which is one of the most patronizing, blatantly fabricated and thinly-veiled plugs for a movie I’ve endured in years. Some studios are so focused on profits, they forget that the audience has an IQ above 12.

And that’s sick…