Ladder is slang for any long gun clip that holds 30 or more rounds. The name ladder comes from the fact that those clips resemble ladders used to climb. This slang is similar to Chicago's mop and 30 poppa slang.. This slang is believed to have been started in Fresno, California, and is widely used in places like Philadelphia. It has been used by numerous rappers in hip hop songs such as Meek Mill's "Y'all Don't Hear Me Freestyle," in which Meek raps, "You gonna think my dog a roofer, brought a ladder with him - My other homie a mechanic, got his ratchet with him - And they shootin' for real, they shooting to kill."