Keeping it 100 is another term for keeping it real. People like it when you are honest and keep it 100 real. Don't lie, don't hoe around, don't cheat. How hard is that? Not only do you want to keep it real with friends, but also with yourself. Used the same as "on the strength", "on my Momma", "swear to God", "real talk", "on everything I Love" "on the for-realla my nicca" and of course "Keep it 100".