Or go on eBay, bid on a fortress fone, and card it. While you're waiting, go down to K-Mart and swipe a ChatterBug as well.
Then when it arrives, you can wire the escrow relay open, install the ChatterBug inside, mount it somewhere that gets a lot of foot traffic, and become very rich very quickly. The unsuspecting victims will pick up the handset, hear fake dialtone, insert money, dial, get nothing, maybe add more money, and eventually get fed up and walk away. All the while, their money is going straight into the cash can - no coin release levers here!
Move the fone around every few days, and watch the dollars add up.
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** Yeah, right. If you follow these instructions, you deserve every bit of what will happen to you. So even if you're the kind of fuquad that thinks this is leet advice, DON'T DO IT.**
edit: make that "chatterbug", not "wirefly". d'oh!