Title text: Good thing we're too smart to spend all day being uselessly frustrated with ourselves. I mean, that'd be a hell of a waste, right?
When asked by Megan what he's been up to, Cueball responds with the (warning: TV Tropes link) suspiciously specific denial, "Definitely not spending every day consumed with worry over stupid things I never talk to anyone about.", which suggests that that is exactly what he's been spending every day doing, but he is hiding it from her (and everyone else). Megan's response "Oh, yeah, me neither" suggests she too is worrying over stupid things but isn't admitting it.
Instead of discussing their mutual worry and possibly making each other feel better, they instead continue to "not talk to anyone about it" and stand in awkward silence.
The title text continues the irony suggesting it's good that they're too smart to spend all day being uselessly frustrated with themselves, but that's apparently exactly what they are doing.
- [Megan and Cueball are chatting. She has hair.]
- Megan: What've you been up to?
- Cueball: Definitely not spending every day consumed with worry over stupid things I never talk to anyone about.
- Megan: Oh, yeah, me neither.
- Cueball: That's good.
- Megan: Yeah.
- [The final panel is silent.]