The Frostee Cream boy is played by famous film director Jim Jarmusch. He wrote and directed Ghost Dog, Broken Flowers, Only Lovers Left Alive—and he dispensed ice cream and French fries to the residents of rural Arkansas. (Source)

Besides French-fried potaters, Karl loves biscuits with mustard. Pillsbury's recipe for honey mustard biscuits would be the perfect thing to make if you ever decided to visit Karl in the mental hospital. (Source)

Lucas Black, who was around twelve when Sling Blade was filmed, first saw Billy Bob Thornton walk and heard him talk as Karl during their first scene together at the laundromat. The young actor just rolled with it and has continued doing just that during his acting career. (Source)

To get Karl's distinctive walk just right, Billy Bob Thornton put crushed glass in his shoes to force a limp. Did he hum that Annie Lennox song to himself, too? (Source)