Allow me to sum up all of south park;

A city bus, carrying the expected cross-section of people, is making its way through the concrete canyons en route to the next stop. As is often the case with city buses, most of the people riding are minding their own business unobtrusively (or trying to), while others are not.

In particular, in the seats toward the rear, a small baby is screaming inconsolably. Maybe it's teething, maybe it has an ear infection, maybe it's simply hungry. No one can really discern much beyond the ear-splitting pitch of the shrieks and the flat familiarity on the face of the child's exhausted mother. Mostly, they're just trying to ignore it.

Near the front, another source of copious din. A man of exceptional size (he could be 6'5 easily, with a profile and musculature better suited to a Neanderthal than a modern man. His manners, though, are similarly retrograde: He bellows profanely into his cell phone, heaving all manner of curses and scatology out loud in an argument with his girlfriend - the other passengers can tell it's his girlfriend, because he has helpfully placed her on speaker-phone for the entertainment of everyone else. The mix between all this and the baby is, you can imagine, quite obnoxious.

Suddenly, a passenger leaps to his feet. He's a young man, possessed of a cocky swagger that suggests he has done very little to earn it - which in turn suggests that his dumpy thrift-store attire is being warn more out of affect than economic necessity. (If only there was a simple one-word shorthand with which to describe such a man...) In any case, he has clearly risen to offer some kind of solution to the noise problem. He strides confidently to the back of the bus, looks down at the wailing child...

...a slaps it - hard - clear across the face.

The baby is stunned into silence (or maybe into a coma, I mean... that's kind of why adults don't generally go around slapping babies, right?) and, needless to say, so is the rest of the bus. It's so quiet, you can hear the aura of self-satisfaction emanating from the young man as he stands arms akimbo over his accomplishment. Finally, one incredulous fellow passenger rises to confront him:

"What the hell is wrong with you, man? You can't hit a baby!"

"Oh! No, no..." laughs the young man, holding up his index finger to indicate that he'll elaborate further once he's done shaking his head with amusement at the passengers' misunderstanding, "It's cool, it's cool. Watch."

He strides, confidently, to the front of the bus, stopping in front of the imposing cell-phone shouter. He draws back his arm, flattens his palm, and delivers a swift slap to the large man's face. As you would expect, the same strike which was devastating to an infant is barely noticed by a full grown (over-grown, if we're being honest) man.

The young man who delivered both slaps, however, stands confidently - smugly, even - among the still incredulous passengers.

"See? It's totally okay - I attack both sides equally!"