On BDSM and the Butt.

In practical terms, the butt is probably the best place to hit someone. It's thickly padded with muscles and fat, contains no vital organs, the bones are sturdy and deep, marks on it won't show in public, and there's no exposed nerves or blood vessels. It's a sturdy piece of anatomy, and it can take a lot of pain without ever turning it into that "oh fuck, something's being damaged" sensation that's a lot more disturbing than pain.

And it's sexy. The upper back is also resilient, and it can be sexy in its own right, but let's face it, there's not a lot of porn of people wiggling their trapezii at the camera. Asses are round and squeezable and they're strong and soft in just the right proportion. They're sensitive enough to stroke with fingertips, erogenous enough to clutch during sex.

And it's humiliating. It's likely where you got spanked as a child--and bent over a knee or the edge of a table you're little more than a child again. It's something you cover in public; to uncover it is impudent, or slutty, or intimate. It's one of the places Cosmo is always telling you isn't good enough. (Which means that hitting it is an act of acceptance as well as dominance; an ass that's good enough to spank can't be so bad.) It's where you poop from, for Chrissake--it takes nerve to let someone see and touch you where you poop.

Because at the center of the ass there's the asshole; one of the body's most vulnerable parts nestled within one of the strongest. It's what makes the ass not just touchable but fuckable. It can receive far more pleasure and pain, and cause far more humiliation. Cruelty or ineptness here would be disastrous. Being fucked in the ass is an act of submission because it's dirty, yes, but more because it's an act of trust. You have to (well, should, anyway) know that your top wouldn't and won't hurt or embarrass you any more than you want.

Although if you want a lot, well... that can be arranged.

Just turn around and stick out your butt.