Someone "Bowling it" walks with the arms swinging out wide to the side, and their body leaning in the opposite direction to balance out the arms swinging. The head may also be moved in an exaggerated manner side to side to futher balance out the huge distance the arm is.
The wider the arms swing, the more ridiculous, and the harder the person in question usually thinks they are. Someone "bowling it" walks with confidence / arrogance and will not move out of the way for people.
Bodybuilding can induce the bowling it effect, they are bowling it, but not in the strict definition where it is more the mental state of the person, than the action that is being referred to.
Self training is necessary to repeat the gait, as rest assured it does not come naturally, further highlighting the show and arrogance of the person that puts on the display when walking.
Bowling it is most often practised by youngsters, and is often acquired during school years, when people have less respect for one another and need to make their way through corridors.
Although I mention the head and body tilt is to balance the arms, I personally wonder if it is not in fact to compensate for the weight of their huge heads, they being big headed people.
Me and my friend look at each other and chuckle at that fool bowling it along the highstreet.