What's the most effective way to teach your baby to ask you if he wants to pee or poop?

Hello, There can be many phrases that can be taught to a child, but what I have experienced with my youngest child is that when the real time comes, she would corner me, and tells me in my ear that she wants to go to poop or pee. So, before she says anything I come to know that she has to go to the loo, when she corners me. I think with time she would know how to just plainly say that she need to go use the washroom.