"I developed my own truck driver mouth," the actress tells PEOPLE with a laugh. But when the cast filmed the final season – which will air Wednesdays (10 p.m. ET) on FX – the gang of tough guys softened up.
"The final days of Rescue Me were terrible," she says. "There were a lot of tears. Especially when people heard, 'That's a series wrap on Denis Leary.' A lot of the guys got really choked up."
Even the man who helmed the series?
"Denis didn't cry, but he was very quiet," says Thorne. "Which is a big deal for Denis Leary."
Still, Thorne says the reaction made her feel good because, "the show touched everybody that deeply," she explains. "This was a family – seven years together. The set of Rescue Me was our playground and our home."
Luckily, she's got a new project to keep her busy: Thorne stars on the new USA series Necessary Roughness, which also airs Wednesdays (10 p.m. ET).
"It's the millennium," she jokes of having two shows on at the same time. "You can TiVo!"
For more on the actress's thoughts on bidding farewell to the firehouse drama, watch the video below: