Can I get (rid of) a Witness?

It is Friday tomorrow.
It is not likely to be pelting down with hailstones.
They will be here - it is my mission to ensure that my vulnerable little offspring are not.

Oh ok, I'm talking about the Jehovah's Witnesses, those fairweather evangelisers, those well-fed, glassy-eyed, smug, thinly-smiling old bags who turn up on my doorstep once a fortnight (except if it's raining) to foist some crap tracts with the production values of a chip cone onto me.

Why do I not tell them to fuck off and burn in some fiery lake of their own lurid imagining?
Well they've got me there. They have somehow sensed that I am a vaguely nice person and will not swear in front of the kids. I don't even want to ridicule other people's beliefs in front of them, 'cause ridiculous as those beliefs undoubtedly are, we know where that kind of education leads.

Pooky rushes to the door every time the bell rings, and as he does with every caller, has told the JWs his name, age and practically his entire life story. All I can do every time they catch us in (and it's not often - I even frequent weekend dad paradise The Wacky Warehouse to avoid them) is pretend that Puggle has just shat herself and I need to change her nappy as a matter of urgency.

Once when I was very pissed off with them (I think they'd aired a Bible in my presence or something) I told Pooky that the ladies had special educational needs and we had to be nice to such people, but no, I wouldn't read their magazines to him and would he like The Very Hungry Caterpillar instead?

HOW do I get rid of the Witnesses?
I'd be very grateful for any suggestions that don't involve a machete, as I can't be pestered washing the blood off the step.