Pasco County Sheriff's deputies say 27-year-old Michael Pratt now faces grand theft charges.
The St. Petersburg Times reports Pratt told the woman he needed to get something from the car while they were watching the movie.
She gave him her keys. When he didn't return, she called him. Authorities say Pratt laughed, then told the woman he'd stolen her car.
She tried contacting Pratt before calling the sheriff's office. Four days later, Pratt called and told her he dumped the car. Deputies found it and arrested Pratt on Wednesday.
He is in the Pasco County Jail. No attorney was listed on Pratt's jail records.