Lindsay Lohan was on her best behaviour on the set of 'Anger Management' this week and impressed the crew by showing up earlyThe 26-year-old actress - who was sentenced to 90 days in a rehab facility last week for lying to police about driving during a car crash last June - "shocked" crew members by showing up early on set in recent days and being extremely professional.A source told Us Weekly magazine: "She has showed up on time and early, and she has been very prepared and professional. Everyone is shocked -- the crew had already planned to stay late in case she was late or didn't show up, but so far, so good!"The troubled starlet - who has been to rehab five times since 2007 - also took some time away from filming to meet a crewmember's children.The insider said: "Lindsay said, 'Oh, I'd love to meet them!' She went over and said hi and was really sweet to them."The actress filmed a guest role for the show this week after being invited to do so by her good friend Charlie Sheen, who is the show's star.The duo became firm friends after filming a cameo for 'Scary Movie 5' last year and Charlie, who has repeatedly supported the actress, even gave her $100,000 to pay a tax bill.But the insider revealed that there is a possibility she will be back on the show again once she completes her court ordered rehab and 30 days of community service, saying: "She is only in one episode but is hoping to do more. There is a possibility she'll be asked back."On Tuesday (26.03.13) the actress revealed on Twitter that she really enjoyed the experience.She wrote: "I just had such a wonderful day on set of #angermanagement with @charliesheen & @LIGHTAARON @SaveTheSociety @jazejazz7 and the entire crew!"Lindsay has now flown to Brazil, where she is set to earn more than $100,000 to promote a clothing company.