Boots
There was a little boy in pre school. At the end of one cold winter day, when all the other children were leaving, the teacher found him crying, so she asked him what was wrong.
He sobbed, "I can't find my boots."
The teacher looked around the classroom and saw a pair of boots. "Are these yours?"
"No, they're not mine," said the little boy, shaking his head.
The teacher and the boy searched all over the classroom for his boots.
Finally, the teacher gave up, "Are you SURE those boots are not yours?"
"I'm sure," the boy sobbed, "When I came to school this morning mine had snow on them."