Racial slur referring to method of throwing belongings by hispanics crossing the border. Term created from illegal immigrants throwing their belongings, (usually boxed items inside a black garbage bag) over a barricade or across a river.
Term is commonly used by hispanics when retelling tales of entering the country illegally.
-"Did you see how fast he got through that wall??!! that slingboxing bastard!!"
-"hurry up! slingbox your stuff over the wall!!"