UV-glowing skulls stamped onto thousands of pounds' worth of UK bank-notes

Shardcore sez, "For the last two years I've been stamping UV skulls on the Queen's face on all the money that I get out of the ATM. There's now thousands of pounds worth floating around the UK economy, visible only to bees and humans with a blacklight.

Given the events in the world's economy over the last couple of years, it seems all the more (im)pertinent."

UK shopkeepers often keep a UV light by the till to check notes to ensure they're not counterfeit.