By using the melody from 19th-century folk song ''Turkey in the Straw'' (a.k.a. children's tune ''Do Your Ears Hang Low?''), 15-year-old Jibbs has crafted an instantly recognizable top 10 hit without paying sampling fees. As it so often goes, ''Chain Hang Low'' is the most memorable moment of his competent debut, Jibbs Feat. Jibbs. The St. Louis teen is an impressive, confident rapper, but he spends most of the disc trying out too many different styles from slow-rolling Houston grooves to Nelly-style pop-rap instead of defining a sound of his own.