The Mean Girls star has been in and out of jail and rehab this year (10) and is currently serving a three-month stint at California's Betty Ford Clinic after failing two court-ordered drug tests.
Lohan's recent probation report stated the actress fears she will be unable to pay the $53,000 (£35,333) fees for her rehabilitation because she "can not afford" it.
But the 24 year old has laughed off her reported money problems in a mocking public service announcement (PSA) in support of the American Jewish World Service on Ferrell's site.
In the clip, the actress says, "Hi, I'm Lindsay Lohan and I'm not Jewish but I am happy to be here. These things pay well, right?"
Ben Stiller, Jerry Seinfeld and Andy Samberg also feature in the Judd Apatow-directed video.