Arnie wants "more juice" when the straw pulls out of his apple juice and he sucks only air. mom pretends to fill his sippy cup by unscrewing the lid and acting as if she is adding more juice. in reality, all mom does is push the straw back down to the bottom of arnie's cup. he acts as he sucks on the straw, pulling the juice into his mouth. mom is wise not to tell arnie that he has plenty of juice, because he is preoperationally: