My 4 year old has on a number of occasions said "I"ll get you with my funny knocker". This is normally followed by him touching us on the arm or chest.
He goes to pre-school so I assume he has picked it up there. I've tried googling it to see if it features in a story but quite frankly it has brought up a raft of slightly dodgy looking websites so I've given up.
Anyone else heard it??