Tori Spelling can crack Jennie Garth up.

When thinking of an upcoming scene from their new ABC Family sitcom, "Mystery Girls," now airing Wednesdays at 8:30 p.m., Garth giggles at the memory of Spelling going for it, making a funny face and using a strange voice.

That's just one reason the two like to work together.

"I feel safe doing some, like, goofy, crazy face and voice because it's my friend. I know she's gonna be there to support my efforts," explained Spelling in a recent interview.

"She knows I love it," added Garth, who readily admits she's the first to break character in a scene.

Unless you skipped the 1990s, you know they were co-stars on one of the most popular TV shows of that era, "Beverly Hills, 90210," about teens living in the exclusive Southern California zip code.

It went off the air after 10 seasons in 2000 but Spelling and Garth have remained friends. They even briefly reprised their roles for the CW's "90210" reboot. Spelling guest starred on a couple of episodes. Garth appeared on the first two seasons.

They never expected to work together full-time again but Spelling came up for the premise and it all fell into place.

On "Mystery Girls," Garth and Spelling play former co-stars of a hit 90s detective TV show of the same name. They've gone their separate ways, until a crime occurs, and the witness will only talk to them. From this, they end up opening a detective agency.

Both actresses also serve as executive producers. They have their hand in the show's look, wardrobe and "every little thing," said Spelling.

"Our personalities are (to be) micro-managers. We can't delegate that much but we're learning," she said.

The two say they rarely disagree on decisions but Garth will defer to Spelling sometimes "because it was her idea."

They chose to do a sitcom because, "it's more fun than doing a drama," said Garth. "The schedule, the hours. We both have a lot of kids so it's like banker's hours compared to doing an episodic show like an hour-long drama or something."

For Spelling, having a sitcom was a career goal.

"I did the best I could on "90210.' Like I tried to make Donna funny. I was in a drama. Everyone else was great at drama but I was like, "I think I'm better at comedy so how can I interject comedy here and there?' and so Donna was kind of goofy and I did things here and there but I was always, this is harder for me. I wish I could do comedy."

The gig also comes at a good time for Spelling's personal life. Her recent marriage struggles with actor Dean McDermott have been documented both in the press and on the Lifetime docu-series, "True Tori." On that, cameras followed Spelling in the aftermath of learning her husband had an affair and he subsequently went to rehab.

Spelling says it's undecided whether there will be more "True Tori."

"It was something that I needed to do. ... I don't know what the future holds," she said.

With all the rumors swirling around her personal life, she felt it was best to document what was happening on camera: "It was the best vehicle to tell my truth." Still, putting her personal problems on display can seem strange to some.

To that Spelling says, "It was something I needed to do so don't feel bad."