lohan-sheen-230.jpgLindsay Lohan may have a 90-day rehab sentence hanging over her head, but she's not letting that get her down or affect her work!

The 26-year-old actress filmed a guest appearance on FX's Anger Management yesterday with Charlie Sheen, and sources on set reveal that Lohan was a dream to work with.

“Lindsay knew her lines cold and her timing was perfect," a source told TMZ. "She was really funny.” Lohan showed up to work 45 minutes earlier and was “incredibly nice,” even taking the time to pose for photos with the crew. “She proved she has talent,” the source added. “You watch her and you know why she became a star.”

Lohan will star as herself, and she'll play a patient who falls for Sheen’s character, Dr. Charlie Goodson. E! News reports that the episode, which will air in April, will make fun of some of the starlet's real-life troubles, and yes, there will be a love scene. Yesterday Lilo tweeted, "I just had such a wonderful day on set of #angermanagement with @charliesheen & @LIGHTAARON @SaveTheSociety @jazejazz7 and the entire crew!"

Sheen and Lohan previously hooked up onscreen in Scary Movie 5, and since then they've become good friends. Last year Sheen lent her $100,000 to pay her tax bill, and in February he offered to split the cost of her AMFAR gala dress. Glad to see him helping her out!