When you are "w" to a word to make it rhyme, it's a way of making something sound cute and enticing or emphasizing its cuteness, especially to a small child. As Phil said, it's a common aspect of Baby Talk, which is how people often talk to babies. For example, "fuzzy wuzzy" implies that the thing is very soft, fuzzy, and appealing.

The idea is to sound like baby-talk, that is, the way a parent talks to a very small child. However, Fuzzy Wuzzy has a meaning too- it was a term that British Soldiers used for warriors from Sudan (I think). It's not an acceptable word now, but at the time the British respected these warriors.