I was going to suggest a turkey call but I guess a whistle would do ok too.
Don't worry about it being illegal or not; cops don't care about collection agencies. Besides you're just responding to their call. Just use of reasonable force for self defence principle as per Section 372 (3) of the CCC.
The "Brian Pitkin Method" is basically the same method that Monty and Angella advocate; the same one that XDebt_Collector and countless others used. (Expect the same results they got and stock up on your stamps, stationary and digital tape decks with lots of memory). Out of the 700 or so posts I've made, there's dozens referring to the "Jackson Method." Typing in "Jackson Method" under "members search" button pops up a few of them. Or try typing in "Optingout" and go to the "I'll save you Olive Oil" thread.
Basically the method exploits 2 very, very, very very, very obvious principles that's are a collection agency's weak spots: (1)They make their living off the telephone, you don't and (2) What goes around comes around. Think of what immediate consequence flows from that - Hammerheads don't like to get hammered; and believe me, collection agents are merciless hammerheads.
And so when I see people writing in that they are mercilessly being hounded by collection agents, I ask (that is, besides why some lucky people get to have all the fun), why they needlessly put up with it.
Ray