chryles wrote:didn't there used to be, or is there still, a similar law here (UK) about defacing a coin of the realm or something?
There did, indeed, used to be a law, however this was repealed, and we brits are now free to mangle any and all UK coinage to our hearts content.
However...the same does NOT apply to bank-notes:
CURRENCY AND BANK NOTES ACT 1928
s 12 Penalty for defacing bank notes.
If any person prints or stamps, or by any like means impresses, on any bank note any words, letters or figures, he shall, in respect of each offence, be liable on summary conviction to a penalty not exceeding level 1 on the standard scale.
That said, it's not illegal to actually destroy bank-notes, just to deface them
