keep it 1000 means: People would claim that they kept it 100 in 2008 to indicate they are being honest and truthful. Inspired by hip-hop, Slate Stone declared that they would keep it 1,000 to distinguish the true from the false. It should be one thousand. The term was first used in West Texas by KSTQ Hot 104.3. (in Community Dictionary, added by Korbin Griffith)