[silisili]

Funnily enough, this reminds me of my Dad's approach years back. After he said no and they'd start again, he'd say "oh sorry, are ya deaf or dumb, boy?" in a way you couldn't tell if he was joking or not.

They'd usually be speechless or say 'neither', and he'd explain that he already said no, so they must either be hard of hearing or their brain's not processing it. Always caught them off guard. I don't remember if it was effective or not in getting them to go away, oddly enough.