DESPERATE and destitute LINDSAY LOHAN is mooching money off of “Two and a Half Men” star Ashton Kutcher – and he feels so sorry for the troubled tartlet that he’s having a tough time turning her down.

Sources say the two had a brief fling years ago, so Ashton feels obligated to let Lindsay treat him like her own personal cash machine!

Although their brief romance was never serious, “Ashton has always had a soft spot in his heart for her, and Lindsay totally exploits it,” said a source.

“She has been asking to borrow hundreds of dollars at a time with the promise to pay him back ‘in a couple of weeks.’ Ashton knows he’s never going to see the money again, but he’s very loyal,” continued the source. “Even to a train wreck like Lindsay.”

Lindsay and Ashton’s friendship dates back to 2003 when she was “Punk’d” on his MTV practical joke show of the same name. She also once appeared with Ashton on “That ’70s Show.” But while Ashton’s career – and bank account – has skyrocketed since then, Lindsay’s life has been consumed by legal problems, stints in rehab and financial woes.

Lilo, 26, is reportedly so broke she’s moved in with her mom on New York’s Long Island. She’s also become unin­surable by any prospective film directors or producers, which has made a career comeback difficult.

“It’s terribly sad,” continued the source. “Lindsay’s broke and she’s burned bridges with so many people. But Ashton never refuses her. He just writes a check whenever she says she needs money.”

Lindsay has also been pressuring Ashton to get her a guest spot on his hit show, but so far he’s managed to put her off. And his days of bankrolling Lindsay may soon be coming to an end if his girlfriend Mila Kunis has anything to say about it.

“Mila is quickly losing patience with the situation,” added the source. “She wants him to cut her ties with Lindsay – the way the rest of Hollywood has.”