We got this book from the library at first, as my son is just beginning to potty train and he adores cows (don't ask!). We read it so often that it quite simply had to become a part of our own collection - even so, if he spies it on the shelves at the library he tries to take it home!
It's a funny rhyming book that is easily memorized, and involves repetition of phrases that my son loves joining in. Of course now when he wants the potty he cries out "Suzie Sue", and on a recent trip to Ikea, he dropped his trousers when he saw a red potty, but that's just the joy that is parenting. I highly recommend this book to anyone with toddlers, potty trained or not. Mij Kelly and Mary McQuillan are a fabulous combo.