You can tell by the "ancient" camera in this photo that it was taken in a time before every young woman had a cellphone with a camera and was doing the duck face pose for selfie immortality. Yet even in those early days, this photo made rounds on the internet because of its startling optical illusion.

It's understandable why -- at first glance, the photographer's arm in this shot appears to be the rear end of the girl in pink; surely, that would make anyone do a double-take!

A quick search will find dozens of collections of funny and "sexy" photos that are the result of tangled arms and legs or of taking the picture at just the right moment. As this photo proves, posing for a shot does not prevent accidents from happening; indeed, in this collection of "30 Crazy/Sexy Optical Illusions" from Just Viral, only 11 are unplanned candid shots!

So... a word to the wise and to the Instagram and Imgur addict: be careful, be very careful. Take a close look at your photo before uploading it; else you could find internet immortality is not what you'd hoped for!

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