The Sole Provider is a store in Springfield Mall. It is a parody of Foot Locker. (It is also a pun on Michael Bolton’s 1989 album, Soul Provider.) The bullies work here.
As Bart and Milhouse wandered through the mall they came across the bullies, who were working at The Sole Provider. The two friends then started harassing the bullies, taking advantage of their boss' rule " No wailing on customers". So Bart takes off his shoe and shows his smelly sock in front of Kearney.
After their boss quit, however, the bullies were able to get revenge on Bart and Milhouse, beating the two of them up and tying them to a web of shoelaces in the store window.
At the time the Squeaky-voiced teen was in a managerial position at the store, the bullies seemed to be somewhat afraid of him, although this was probably just because they didn't want to lose their jobs.