Atlanta producer Lil Jon works so hard he sometimes loses track of his own, um, tracks. Having scored big with the Ying Yang Twins and the Kings of Crunk last year, Jon just knew he was on his way to the next level when he created and cowrote the first take of ''Yeah!'' with R&B icon Usher. But there was a problem. They'd recorded the song over an infectious, synth-happy music bed that Jon had already given to Jive Records. When Lil Jon later ran into friend and Jive recording artist Petey Pablo, he got a big shock. ''Petey plays me the song ['Freek-a-leek'],'' recalls Lil Jon. ''I'm like, 'That's the same [music I gave]Usher.' He's like, 'We've recorded, mixed, mastered, and put it on vinyl already.' So, I'm like 'F -- -.''' With so much invested, Jive wouldn't give up the cut. To make matters worse, L.A. Reid (then still running Usher's label, Arista) found out about the mix-up and started ''going crazy.'' There was nothing for a prolific producer like Lil Jon to do but jump back in the studio and whip up an equally catchy replacement track. The result: Usher's ''Yeah!'' still rides the top of the charts, with Petey Pablo's ''Freek-a-leek'' moving up steadily behind it. Nice save, Jon.