Continuity mistake: Daria arrives at school without her glasses (her choice). When the scene changes to Mr. O'Neil's class, first shown from the back facing O'Neil and the backside of students, Daria (sitting on the left of the screen) is shown from behind and her glasses are showing on her face (as usual). When Daria is next shown talking close up in the remainder of the scene, she is without her glasses again.
Continuity mistake: When Jane (who has blue eyes) first meets Tom and talks to him, her eyes become green at one point, then become blue again.
Answer: "Mack Daddy" was a 90s phrase meaning "Ladies man," and Mack simply doesn't like the stupid nickname.
Brian Katcher