From the time my kids were born, my wife and I have kept a journal of all the funny and outstanding things they say and do. It includes how they said words when they were learning to talk, and some stories about what they thought things meant.
An example, when my son was about 3 his asked his mom, "What's an ami?". She asked him what he was talking about. He said "When people are talking and say "My ami", what are they talking about?".
The kids love to have us drag the journal out and read to them about the funny things they said and did.