This stands for the screwed up click which is located in most likely houston texas.
Paul wall is repping for the S.U.C.
The Screwed Up Click is an assortment of rappers from the southside of Houston, Texas started by the late DJ Screw. After appearing on numerous screw tapes and spreading their name throughout southern hip hop, they have become well respected and have earned a proud reputation. Despite the deaths of several members and the incarceration of others, the S.U.C. continues to represent for Houston and remains a strong presence in the southern hip hop scene.
The founding members of the S.U.C. are Screw himself, Lil' Keke, Fat Pat, Big Hawk, Mike D., Big Pokey, and the Botany Boyz (C-Note, Will-Lean, D-Red).
Other members include Woss Ness (Big Steve, Big Bee, Lil' Head, Mistah Luv), Big Jut, Big Moe, Z-Ro, Lil' O, Trae, Dat Boy Grace, Big Mello, C-Ward, Head, Lil' 3rd, Mr. 3-2, E.S.G., Clay-Doe, Lil' Flip, Yungstar, Wood, Al-D (Screw's brother) and others. In addition, UGK and South Park Mexican are considered "Screwed Up Affiliated". 3rd Ward/South Houston is the groups place of orgin.
The S.U.C. is running the South like a race