Hey Strod, Caps just means that one is shouting (as you yourself mentioned). So, it is appropriate for Petey as well, as he has to shout to get the attention of Alice who is shouting herself. Also, it is a way of saying that Petey himself is annoyed :)
…net that he knew of… is correctjust emphasizes that at least Dad and Mom are not having a baby; maybe Mom and someone else might have one. So, he doesn’t know of it. :)
Hey Strod, Caps just means that one is shouting (as you yourself mentioned). So, it is appropriate for Petey as well, as he has to shout to get the attention of Alice who is shouting herself. Also, it is a way of saying that Petey himself is annoyed :)