1) Attendees at a Bitcoin event are each given a physical Bitcoin (from a trusted source and perhaps in paper form to reduce overheads) that contains zero balance.
2) Each attendee then sends an specific amount (say 10 BTC) to their physical Bitcoin's public address.
3) Swap physical Bitcoins of the same amount with another attendee (after checking balance and making sure private key is still hidden).
Anyone tried this yet?
4) The honey pot is then cracked open, licked clean, and wrapped in yellow tape by DEA agents who have been watching you for a while. IRS can come, too.