South Park is the most consistent and actually gets better with age, as did King of the Hill. However, early Simpsons is still the best.
Grandma: [singing] How many roads must a man walk down before you can call him a man?
Homer: Seven!
Lisa: No, Dad, it's a rhetorical question.
Homer: Rhetorical, eh? Eight!
Lisa: Dad, do you even know what "rhetorical" means?
Homer: [incredulous] Do I know what "rhetorical" means?!