On Friday, the sharp-tongued Rivers took to her Twitter to slam Lohan in a series of scathing Tweets.
"Lindsay Lohan is so dumb. Her idea of being sworn in is cursing at the judge," wrote Rivers, in reference to the star's four-letter-word manicure.
She also slammed Lohan's well-documented partying – "I was just reading about the new Lindsay Lohan diet, which is all liquid. 80 proof" – and referenced the judge who delivered her 90-day sentence. "Lindsay Lohan had 'F-ck you' painted on her nails. What people don't know is that the judge had 'Eat me you party skank,' painted on hers."
Several hours later, Ronson got in on the Tweeting to defend Lohan.
"Hey Joan Rivers," she wrote. "You have collagen older than Lindsay, pick on someone your own age, oh wait I guess people that old can't hear."
Early Saturday morning, Lohan re-Tweeted the message and wrote to her ex, "thank you. ;)"