A Toddler's Rules of Possession:
1. If I like it, it's mine.
2. If it's in my hand, it's mine.
3. If I can take it from you, it's mine.
4. If I had it a little while ago, it's mine.
5. If it's mine, it must NEVER appear to be yours in any way.
6. If I"m doing or building something, all the pieces are mine.
7. If it looks just like mine, it's mine.
8. If I saw it first, it's mine.
9. If you are playing with something and you put it down, it automatically becomes mine.
10. If it's broken, it's yours.
-source unknown, but probably someone who had a toddler. This is dead-on.