Our boys are bell trained. We have a huge bell hanging on our patio door low enough for them to reach it. When we would take them out to potty we took their paw and hit the bell several times and would tell them "potty, outside, potty, outside". They picked it up pretty quick too, only about a week or two. We did take them out every couple hours at first when we were training cause we didn't want to wait for them to have an accident to ring the bells. When they need to potty now they give that bell a good wack to make sure I heard it and then come and find me to make sure I am getting up. And if I don't right away they will stand at the door hitting the bell. And you can say for them to potty however you choose, we just thought those were the two simpliest words to use at first. Now I can just ask them when they ring the bells "do you need to go outside and use the bathroom?" and they understand.