Ever been to the Leaning Tower Of Pisa? If you have, chances are you've had your photograph taken "holding it up" with your arms outstretched.
Ah, forced perspective, eh? Always a giggle, be it with Paris's Eiffel Tower or Seattle's Space Needle - but it does tend you leave you open to a pretty easy-to-carry-out prank.
YouTuber 'JegStuffoInfo' here calls it 'troll high-fiving', which essentially means that you high five people while they're offering up their open palms to the sky. Tonnes of fun, we can all agree.
And if this little prank-a-thon has piqued your interest in such childish activities, here's our video gallery of professional prankster Remi Gaillard doing his thing, starting off with this ludicrously popular 'Real-Life Mario Kart' video.