Who doesn't like having their brain momentarily confused by carefully concocted visual stimuli? Makes you feel mortal... well, it makes your mind feel mortal. Check out this photo from psychologist Richard Wiseman's blog, Quirky Mind Stuff.
As you can see, there are three cars, with the one furthest away looking seemingly the largest. But hey, this is an optical illusion, so of course things are not what they appear...
If you compare the vehicles side-by-side, you'll find they're all the same size. Surprise! Alex Santoso over at Neatorama whipped together an animated GIF to that highlights the consistency of proportions.
He then goes on to point out that this is an example of the Ponzo illusion, which states that the background of an image can make it difficult to judge the size of objects in the foreground. Thanks, puny human perception.