It's advisable to avoid complimenting a woman at all when she's walking along the street, because it's going to appear like harassment and sexism rather than you being nice. But the guys from NelkFilmz have figured out a way to do it in public without getting a knee to the groin or attacked by an angry boyfriend.
These pranksters are able to get away with it because, after one of them throws down a "Nice rack" at a woman minding her own walking along the street, his friend then walks into view holding... a nice rack! Or some nice melons or a couple of chicken breasts. You get the idea.
Cue some confused and bewildered women, until they realise they're not the intended target of the compliment. It's an incredibly childish and stupid prank, for sure, but against your better judgement you'll find yourself raising a smile. Damn them.