My son (4) loves the song "I Am Jesus' Little Lamb." He loves it so much that now he apparently thinks it's his personal possession and private property. This morning, our daughter (5) was sitting in the kitchen waiting for breakfast and singing "I am Jesus' little lamb. Ever glad at heart I am ..." Just then, my son comes running in and angrily yells, "No!!! That's MY 'I Am Jesus' Little Lamb'!!!"
I tried explaining the whole "Public Domain" thing, but he didn't buy it.