flab means your yapper, gasterin means what you're yappin' and nonsense, well, you know what nonsense means.

When you go to get your nails done, these are the nonsense sounds you hear the orientals yelling at each other.

when something is so ridiculous that it requires the word nigga in it.

This type of 69 is what happens after a long, grueling day at the office. The male wants to get right down to business so the only thing taken off is the pants and underwear. With his white collared shirt and dress socks still on, he proceeds to sit right on the face of his female counterpart. The male must ALWAYS be on top, it's part of the "no nonsense" label.

having or showing a lack of common sense or judgment which causes foolish or unacceptable beliefs and behavior

Something non-white people use to describe ridiculous things white people do.

When someone makes up a silly little definition you tell them that they are talking utter nonsense.
Strangley enough, the majority of definitions on Urban Dicitionary fall into that category.