I started out with "sssss" (no p LOL) and that worked very well for peeing. I also said things like, "Oh, you need to pee?" and as dd got older, I noticed she started associating the word "pee" with peeing, as well. So, it got to the point (when she was about a year old), that I could tell her, "Pee." and she would. I don't think it really matters what the cue is as long as you're consistent with it.
For pooping, I was self-conscious making the grunting noise, but I've noticed that that *does* seem to work better than anything else. Perhaps b/c pooping takes more concentration?
For pooping, I was self-conscious making the grunting noise, but I've noticed that that *does* seem to work better than anything else. Perhaps b/c pooping takes more concentration?