He is a dog, after all. I'm surprised that Snoopy's amazing, candy-detecting nose failed to realize Charlie Brown had no candy on him.
Here is introduced the second of Peanuts' one-joke characters, and the first character to eventually leave its cast. 'Pig-Pen' lasts until nearly the end of the strip because there have always been, and could well always be, dirty kids. Poor ol' Charlotte Braun's niche gets taken up by Lucy pretty quickly though.
How weird is it that CB's friends tend to call him "Good Ol'" Charlie Brown, and that he remarks upon it?
This is one of those strips where the setting changes from panel to panel in such a way that it implies that the conversation is longer than we're seeing on the page. Particularly, between panels two and three, Violet and Charlotte suddenly go from standing on a path to sitting at a curb, and Charlie Brown has had materialize a tree to ineffectively hide behind -- which suggests that Charlie Brown has been stalking the two to eavesdrop on their conversation.
Charlotte's mouth in the third panel is pretty funny. I think, some time later, some of Charlotte's character was used for Sally; the hair is somewhat similar, and she has a similar head shape.
Snoopy shows distress very well. And I love how Charlotte doesn't even look particularly distressed when she shouts in the last panel. The reactions of Charlie Brown and Snoopy serve to illustrate her volume.
I don't think this will be the last time we see those words spoken. Scribble of ire!