The Origin of ‘Clam Up?’

Really? Now that's progress!
(I don't watch that show so wasn't aware of it)

I have spent a lifetime helping non-New Englanders who say things like 'KWA-hog', 'Kwaog' etc.

Quahog is the name of the town where the characters live. Kids there go to James Woods high School. Adam West is the mayor.

Up in Maine, clams is the "Steamahs" which are the ong necked variety. Quahogs (CO' hogs) are what, in New Jersey and Tidewater states we all call
Little necks, or cherrystones, Top necks or Chowderclams (also known as piss clams).
We southerners mostly eat the clams of the genus Mercenaria while New ENglanders eat the genera Mya and Macoma (although the ranges of these clams overlap, each is more common in their geographic ranges since New ENgand clams tend to be long siphoned "desmodontia" types).
I remember once lecturing some student kids over clams and beer when I burped out the entire word Demosdontia and thus acquired a whole new enhanced status among my students.

Ahaha..priceless!

Just re-reading this thread and enjoying the witticisms.
... also getting psyched up for my next 'New England Sojourn' (in about ten days) which will surely include the usual "seafood feeding frenzy"

Chlamydia? Yikes! STDidious.

Happy as a clam.

Patient as an oyster.