Bleak Peanuts

There are plenty of strips with Charlie Brown striking out, but this one from June 1967 seems harsher than most:

I think it's the irony of the camp sign at the end that does it. Sure, that's the source of the joke, but it's also the source of the cruelty. It's not just that Charlie Brown struck out and the other kids mocked him, it's that so much more was promised to him that he didn't receive.