For efficiency and quality control, perhaps a custom
ink stamp is in order.
Maybe include a cheeky message as well:
[WARNING! Obsolete Currency. Replace with Bitcoin.]
That's a good idea, and I like the notion of a cheeky public service message instead of merely "bitcoin.org" by itself. Perhaps a quote like this:
Paper money eventually returns to its intrinsic value -- zero.
The use of a rubberstamp was also suggested by
Mike Gogulski in the original thread:
The Conspiracy wants you, children. Oh, it wants you bad.
After I first saw "They Live" in late 1990, I had a rubber stamp made reading "THIS IS YOUR GOD" in big block letters of a size suitable for US banknotes. I'd stamp every one of the things that came through my hands for a year or two after that.
Nowadays I walk into a Tesco in Slovakia and buy something upstairs with a 10 note, getting a fiver back plus some coins. Unbeknownst to me, the five-euro note has a small tear on one corner. Take that note downstairs in the same Tesco, right afterwards, and try to pay for something and they'll refuse to take it. Sorry, you'll have to go to the bank ---and show ID--- to get the bloody thing replaced. Useless fucks.
So, my thought for this little bit of guerrilla marketing: Get a *small* rubberstamp made reading "bitcoin.org". Get some blue ink and dilute it down to something approaching the background of the 5 note. Stamp in an area where the mark won't be obtrusive, and not near the major security features. Make piles of them. Plenty will pass with no scrutiny at merchants, and at the end of the day you can always get a banked friend to take the pile you got tired of to his/her bank and ask for replacements, complaining that they've been collecting in the shop till.