Mary-Kate Olsen spent her second day on the set Tuesday of ABC’s comedy Samantha Who for a one-episode appearance this fall, the network confirms.

Olsen, 22, plays a self-destructive bad girl who reminds Samantha (Christina Applegate) of her younger self, but on the set she was all business, Executive Producer Don Todd tells PEOPLE.

“She showed up alone, ready to work, is great on set and is serious about the job,” says Todd. “This is a girl who’s been in front of the camera almost literally her entire life. She’s smart, and she knows what she’s doing.”

Olsen has been stepping out in comedies as of late – she starred as Tara Lindman on Showtime’s Weeds last year – and can be seen opposite Ben Kingsley in the film The Wackness, which hits theaters on July 3. –Pamela Warrick

Who would have thought that Justin Timberlake would one day be a porn star? Unfortunatly, he is not one in real life, just a wannabe porn star in his new movie “The Love Guru.”

The pop singer sports a dodgy ‘tache, big hair, tiny speedos and little else as Jacques Grande in “The Love Guru.” Grande is a professional skater and aspiring porno actor who has stolen away the wife of a rival hockey player whose career has subsequently gone on the skids.

Austin Powers star Mike Myers plays an Indian guru who makes people fall in love and he attempts to break into the US self-help market by resolving this “triangle of lurve”.

Jessica Alba, Ben Kingsley and Jessica Simpson also star in this ridiculous comedy along with Verne Troyer, who played Mini Me in the Austin Powers series.