When they talk about a designated driver, they don't mean a 12-year-old girl.

But preteen Sydney Hughes of Old Hickory found herself behind the wheel of a car instead of in a sleeping bag early Friday, after a sleepover-gone-wrong ended up with the mother of a friend passed out.

Lori Michelle Rock, 35, of Rayon City was ''drinking very heavily'' and ''became so intoxicated she passed out several times while driving her vehicle on the interstate,'' police reports say.

Rock was being held in Metro Jail last night in lieu of $60,500 bond. She was charged with two counts of contributing to the delinquency of a minor, three counts of reckless endangerment in a motor vehicle and one count of public intoxication.

Sydney and two friends took turns driving on Broadway at Interstate 40 in an attempt to get home and had a minor wreck. They said the 35-year-old woman had taken them out to see her boyfriend.

Sydney has been allowed to shift gears before in a car, she and her father, an auto-body worker, said. The vehicle Friday was a stick shift, to make the night more harrowing, but she was able to drive it.

''I didn't even know she could drive a stick shift,'' said her father, Jerry Sitz. ''But I think she did a pretty good job, considering what happened.''

Also in the car was Rock's 13-year-old daughter, Arissa, and another passenger, Jessica Stokes, 12, according to the police report.

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