Thing

I found a Thing the other day and wondered what to do
Dad said, "That's fine, but it's not mine, 'cos mine's a sparkly blue."
"It's not mine either," said my Mum, "don't bring it in the house...
You see those marks? They tell you it's been nibbled by a mouse."
"It looks like one I used to have," said little Freddie Gibbs
"Oh yes?" we cried, and rolled our eyes. He tells such awful fibs
My teacher wasn't too impressed. She took the Thing away
She locked it in her cupboard and she kept it there, all day.
I'll show it to you, if you like. I'm sure you'll say, "Gee whiz!"
But just remember it's all mine. I wonder what it is?