Popcorn Balls

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.