I have answers!!
Clyde is easier than calling them a **** codhead; pop used Charlie a lot. Better for kids in the car than “ a**hole”. No particular significance. 
Grundoon is the “Grundoon Chile” is from the comic strip Pogo ( one of the best ever) by Walt Kelly. Google it -you might be surprised!
Pop was my grandpa.
Thanks guys.  I never asked about Grundoon.  37 years later, I finally know I'm from a comic strip.   
Ahh, yay!  I mean, Larrabee and I were both completely wrong in our guesses, but yay!  Answers!
I did Google Grundoon (now that I know how it's spelled!) and Wikipedia says this:  "Grundoon: A diapered baby groundhog (or "woodchunk" in swamp-speak). An infant toddler, Grundoon speaks only gibberish, represented by strings of random consonants like "Bzfgt," "ktpv," "mnpx," "gpss," "twzkd," or "znp." Eventually, Grundoon learns to say two things: "Bye" and "Bye-bye." He also has a baby sister, whose full name is Li'l Honey Bunny Ducky Downy Sweetie Chicken Pie Li'l Everlovin' Jelly Bean."
I guess the baby sister's name would've been too long to call you.  
