The Spock Five is not only a legal tender for the media age, it's a Canadian cultural phenomenon. Canadian five-dollar bills (blue in colour!) printed before 2001 feature the bust of Prime Minister Sir Wilfrid Laurier, who looks uncannily like Star Trek's Mr. Spock. Sir Wilfrid, elected in 1896, likely had no idea that his mug would one day be the butt of a very Canadian prank: the multilation of his face into the likeness of Spock himself.
The stamp used to produce such an image on the poor man's face is a simple rubber stamp in the shape of Spock's unmistakable haircut and upturned eyebrows. One simple haircut's difference is enough to turn The Right Honourable Willy into a venerable Vulcan, complete with fudged 'pointy ears', marked with an absence of ink high up past where a normal ear would go. It is not altogether uncommon to receive one of these bills; the whole of Canada appears to be in on the chortle. And yes, the defacement of currency is a federal crime in Canada.
Unfortunately, with the issue of Canada's 2001 Journey series of bills, the Spock Five has been 'stamped out' for now. The first Francophone PM's face is fuller and turned further to the side, making the comparison to Spock harder to draw. But, while older bills are still in circulation, you too can Live Long and Prosper for as far as five bucks will take you.