Lost

Brian had just fallen asleep, when the doorbell pulled him back into reality.
He got up, slouched along to the door and grabbed the receiver off the retainer.
"Hello?"
From the earpiece sounded Janet's voice:
"Darling, could you please let me in? I must have lost the key."
"OK", he grunted and pressed the 'OPEN' button.

When Janet entered the room, Brian had pondered the case.
"Sweetie, didn't you say you had forgotten your key at your friend Sarah's?"

She put her arms round his neck.
"Well", she said in a velvet voice,
"Yes. The one I've lost was yours."