An American tourist in County Clare came across a little antique shop in which he was lucky enough to pick up, for a mere 200 Euro, the skull of Brian Boru.
Included in the price was a certificate of the skull's authenticity, signed by Brian Boru himself.
Fifteen years later the tourist returned to Ireland and asked the man from Clare, who owned the antique shop, if he had any more bargains.
'I've got the very thing for you', said the shopkeeper, 'It's the genuine skull of Brian Boru.'
'You cheat', exploded the American, 'You sold me that fifteen years ago', and producing the skull added loudly, 'Look, they're not even the same size.'
'Ah, said the seller, 'but this is the skull of Brian Boru when he was a boy.'