T-theme: I think rain is a symbolism of a big shock or big memory. Because the ran got into his head, he has certain odd behaviors. Walking slowly, stepping softly... Above many possibilities that can represent this big shock event, "love" is the symbolism of rain in my opinion. He says all he hears as he lies in his bed is a slishity-slosh of water. This means he's just full of thinking about his lady (?) or love all day long, since he meets her like rain dropping. I think Silverstein is funny and genius to use brain instead of heart to indicate love;therefore, it gives more strong impression of love effect. Besides, he cannot handstand because he can overflow. I think this means he cannot stand himself anymore to deny the truth of love, or he is just at the edge right before exploding his joy or happiness of love. At the shift, like everyone who become weird and behaves differently than before, author has same consequences of love that can make people think, "I think he changed somehow.