Question 1: Is panel 5 a Geezer or a known fixture of American culture?
Question 2: Is “Marcia, Marcia, Marcia” a Geezer, or perhaps an anti-Geezer? A cultural meme more likely to be known by the young?
From Andréa and chemgal.
And another one from chemgal. This one has to be a Geezer, right?
Comics I Don't Understand 
Wrong Marsha/Marcia spelling I guess.
Is that an Ashkenazi/Sephardic difference?
Brian poses the question:
Is that an Ashkenazi/Sephardic difference?Kidding aside, the girls named Marsha in my high school (of my acquaintance) were Jewish, and when I became aware of the Marcia spelling I assumed it was mostly a gentile name, and I wasn’t even sure of the pronunciation being the same.
I have no idea where the word “gentile” comes from (looking it up now would spoil the joke), but perhaps the reason that I don’t like the term is a subconscious (“Freudian”) association with “genitals“. To be perfectly honest, I would prefer to be called a “goy”.
Mormons also use “gentile” to non-Mormons, although I don’t think they would apply it to Jews.