The whole "Most Excellent Promise" scene.
Elliott: Michael, he came back.
Michael: (feigning shock) He came back? He came back? (pretends to be attacked) Oh, my God!
Elliott: One thing. I have absolute power. Say it. Say it!
Michael: What have you got? Is it the coyote?
Elliott: No. Look. O.K. Now, swear it. The most excellent promise you can make. Swear as my only brother on our lives!
Michael: Don't get so heavy. I swear.
Elliott: Okay, stand over there. And you'd better take off your shoulder pads.
Elliott: You might scare him. And close your eyes.
Michael: Don't push it, Elliott.
Elliott: I'm not coming out until your eyes are closed.
Michael: Okay, they're closed. Mom is going to kill you. Eeeeghh!
Elliott: Okay, swear it one more time.
Michael: (as Yoda) Absolute power you have! Eerrp!