When you think about human anatomy, it seems strange that a single middle finger could exercise total control over someone's spine, but when the mood is right and the ropes are tight, one little phalanx bone can make any back arch.
Heck, it's not even the strength of the finger that's doing all this; it's the skin! Never take your fingerprints for granted, people, because there's someone out there who is dying to feel your unique brand of homegrown texture grazing the tip of her clit.
[Via The Sea of Sin. Have a gif you'd like to see us feature? Email us!]