Trevor says that the only time he gets to drink out of a glass is when he finds one all by itself and with no human in sight. Then of course he knocks it down, spilling its contents, because his head is too big. He wants Edwina to know she is one lucky kitty to be offered a drink from a human's cup. He will probably never live to see that happen, even if he uses all of his 9 lives, although he was allowed to lick out the insides of his mommy's yogurt cups before he got diabetes.