Ernie And Bert Have A Snack

Ernie and Bert are sitting down with pizza and juice. Ernie's serving is noticably larger than Bert's.
Ernie: "Okay, Bert, here's your glass of ice-cold delicious grape juice, and here's my glass of ice-cold delicious grape juice, and here's your slice of cheese, Bert, cheese, anchovy, and pepperoni pizza, and here's my slice of cheese, anchovy and pepperoni pizza. Ready to eat?" (Picks up slice)
Bert: "Hold it, Ernie, hold it! (Ernie puts slice down) Do you notice anything? Take a real close look. I want you to take a look at my glass of grape juice and I want you to take a look at your glass of grape juice. And I want to you to take a look at my slice of pizza and I want you to take a look at your slice of pizza."
(Five second pause.)
Bert: "Well?"
Ernie: "Well what? It all looks delicious, let's eat!" (grabs slice again)
Bert: "Not so fast! (Ernie puts slice down) Ernie, you have much more grape juice in your glass than I have in my glass. And you have much more pizza on your plate than I have on my plate."
Ernie: "Is that so?"
Bert: "Yes, it is. And I have much less grape juice in my glass than you have in your glass. And I have much less pizza on my plate than you have on your plate. I have less, and you have more. I wonder how that happened, hmm?"
Ernie: "Oh, gee I'm sorry. I can fix that!"
Bert: "You can? Well -- (suddenly Ernie starts gobbling pizza) I don't mean fix it THAT way--Ernie! (Ernie ignores him, starts slurping his juice loudly) Ernie--is that your idea of fixing it?" (Ernie sits back, satisfied, examining pizza and juice, Ernie's is now much smaller than Bert's.)
Ernie: "There, Bert, it's all fixed! Now you have more juice than I do and I have less juice than you do, and you have more pizza than I do and I have less pizza than you do. See, all better!"
Bert: "I don't understand......"
Ernie: "But wait a minute--that's not fair, I have less, and you have more--" (Bert starts to protest)
Bert: "But, Ernie, you just ate all that--"
Ernie: (at the same time) "I better fix this too--" (Ernie starts drinking Bert's juice, slurp, slurp, slurp)
Bert: "But you had your grape--and you had your pete--pizza and--"
(Ernie has finished all but an inch of Bert's juice, turns to Bert's pizza.)
Ernie: "And now I better eat some of your pizza." (starts noshing down)
Bert: (He is resigned, walking away) "Enjoy it, Ernie!"