Acting excessively silly, or wildly exaggerating a stereotype for fun hamming it up
Did you see the girls with the bachelorette party? Oh, the ones at the bar wearing feather boas, smoking cigars, and drinking blowjob shots? Yeah, they were totally hamming it up for the camera.
Used to describe a person, usually a nagging wife, that constantly babbles and complains about even the smallest of issues. This person will usually express their resentment or displeasure in a public place such as a grocery store or restaurant.
Yammering Netty literally means Clamorous Toilet; from the
verb Yammer: To utter or say in a complaining or clamorous tone; and the noun Netty: The British slang word for public or outside toilet. - See also: Chatter Box
Herold took Alice out to a nice restaurant and all she did was babble about how he never takes her anywhere nice. Alice is such a Yammering Netty.