Lessee the origins of these nick names...
G-Dog, because he's screwing his secretary and everyone knows it, or he just looks like a dog.
P-Money, because that's the one that controls the purse strings.
Big Anne, because all the kids think she's fat.
And there you have it, an entitled child's version of respect, "I'm dissing you to your face". However, since the think their kids and kid's friends are including them in their world, parents lap it up.
"It truly is the one commonality that every designation of humans you can think of has, there's at least one asshole."
--Me