Holy crap, Wicked! That is an awesome list.
Another great episode was Grandpa vs. Sexual Inadequacy.
Grampa: Welcome home, son. I broke two lamps and lost all your mail. What's wrong with your wife?
Homer: Never mind, you wouldn't understand.
Grampa: Flu?
Homer: No.
Grampa: Protein deficiency?
Homer: No.
Grampa: Pneumonoultramicroscopicsilicovolcanoconiosis?
Homer: No.
Grampa: Unsatisfying sex life?
Homer: N - yes. But please, don't you say that word.
Grampa: What, seeex? What's so unappealing about hearing your elderly father talk about sex? I had seeeeex.
Grampa: [throwing a bottle of tonic to Homer] Here you go, ya ingrate. Think of me when you're having the best sex of your life!
Homer: Excuse me, sir, you look like a man who has trouble satisfying his wife.
[man punches Homer in the face]
That and the whole childish innocence of thinking the parents are reverse-vampires.