THAT is a punch. Though in Myth Busters they proved that its not possible to be punched so hard you would be kicked out of your socks, but well, this seems real different!
From the way the guy flew, it should be possible for his clothes, save the tight articles, to fly away. Since street gangsters seem to like wearing loose clothing and lack properly-tightened belts, I can see this happening if someone could punch you that high.
Shaomu said: I can see this happening if someone could punch you that high.
It's not so much the height or even the force of the punch itself that does it here. The centripetal force as a result of the rotation his body experiences is ultimately the reason his clothes come off. For instance, a punch of equal force directed at the abdomen that causes the punchee to accelerate straight back with no rotation would have been less likely to cause his clothes to slip free. This is because the component vectors of the forces acting on the clothes directed along the axes of his limbs would be much weaker in that case, whereas in the image's case, the centripetal force is directed almost exclusively along the lines formed by his limbs thus pulling the clothes off in the reverse way one might put them on in the morning.
However, your point about a reduced normal force (and thus reduced static friction) between his clothes and his body due to the loose-fitting articles is well taken.
THAT is a punch. Though in Myth Busters they proved that its not possible to be punched so hard you would be kicked out of your socks, but well, this seems real different!
It could be attributed to the rotational forces he experienced.