Dixons Recycle

To inadvertently introduce to someone what you believe is a new piece of information, when in fact you have forgotten that they were the very person to tell you about it in the first place.

To present to someone as new something which is actually secondhand from them.

Have you heard of this great band called The Pixies?

- Don’t Dixons Recycle me, I was the one who lent you the cd!