Homer Simpson replaces King Juan Carlos on Spanish coins

Don Juan Carlos's regal half-profile topped by a full head of curls had morphed seamlessly into the pop-eyed, big-nosed, bald-headed features of beer-glugging Homer, complete with his 5 o'clock shadow.

"The coin must have been done by a professional" Jose Martinez said when he found it in the cash register of his sweet shop in the Asturian town of Aviles.

"It's an impressive piece of work."

The anonymous defacer with a sense of humour had not taken his scalpel to the other side of the coin, which displays the map of Europe. But the high quality of workmanship has prompted speculation that other retouched euros might be in circulation.