Popcorn Balls

2 cups sugar
1 1/3 cups water
1/2 cup light corn syrup
1 teaspoon white vinegar
1/2 teaspoon salt
1 teaspoon vanilla extract
18 cups popped corn
Directions
In a medium saucepan, combine sugar, water, syrup, vinegar, and salt. Cook over high heat until mixture reaches 255 degrees F (hard-ball stage) on a candy thermometer. Stir in vanilla. Pour over popped corn, tossing gently to coat. When mixture is cool enough to handle, press popcorn into 3-inch balls with lightly greased hands. Cool completely on waxed paper.