Mean Girl! 'Childish' Lindsay Lohan Clashed With Legendary Singer Chaka Khan In Rehab -- The MAJOR Blowout Revealed

When Lindsay Lohan moved from the Betty Ford Center to Cliffside Malibu she joined another famous face, legendary singer Chaka Khan — who RadarOnline.com has exclusively learned left the treatment center early because she couldn't stand Lilo's diva behavior!

According to a source who attended rehab with Lindsay, 27, the Mean Girls actress arrived to Cliffside just after Chaka and was immediately disruptive to everybody in the program and when Chaka tried to set her on the straight and narrow, the conversation ended in a complete blowout.

"Chaka was really cool about everything at Cliffside, but Lindsay just pushed all of her buttons to the point where she was aggravated and tired of Lindsay's sh*t," the former patient told RadarOnline.com in an exclusive interview.

"Lindsay was just doing stupid stuff for attention, so Chaka told her she was childish and told her to grow up. She never lost it, but started yelling at Lindsay. Told her to knock it off, asking her if she came to rehab to get well, or just to piss around."

Things got so heated between the two that the source tells RadarOnline.com 60-year-old Chaka eventually had it with Lindsay, telling several of the patients she "hated" Lindsay.

"Chaka was so annoyed with Lindsay. It got so bad that she refused to get in the same car with her or go to the same meetings with Lindsay,: the source said.

"So Cliffside had to change everything up schedule wise so the two were never together."

Chaka — who has admittedly struggled with drug abuse and alcoholism in the past, spending several stints in rehab centers — left Cliffside a week early because she couldn't stand Lindsay, the source claims. 

"Chaka told me she was leaving early because she couldn't stand Lindsay," the source told RadarOnline.com.

"Lindsay caused such an uproar that administration basically said to the patients, 'If you can't take it and you want to leave, leave.'  The next day a guy that had already left because of Lindsay came back and helped Chaka with her bags and stuff and took her from Cliffside."

Siding with Chaka, the source said they feel bad Lindsay drove so many away from the treatment center.

"Chaka's a strong woman and her time at Cliffside did help her get a lot better. She's a positive lady and quite interesting, in a good way," the source told RadarOnline.com.

"She just needed the strength and at the end of the day she got what she was looking for."

Calls to Chaka's rep for comment went unreturned.