The comic’s joke revolves around a misunderstanding about what the new “sentence generation function” added to the robot Joy actually does.
Makira proudly explains that Joy can now automatically generate text based on prompts like “write a scene between these characters.” Lunarl, intrigued, immediately imagines asking Joy to create a story about “Makira and Popolka’s dramatic, passionate 24–32 page tale.” The implication is that she’s thinking of something romantic or possibly risqué.
She quickly realizes that saying such a prompt aloud would make Joy immediately start generating the story on the spot, and since it would be “inappropriate for minors,” that would get her in trouble. Flustered, she stops herself just in time.
Makira, realizing what almost happened, nervously points out that Joy starts writing the moment it receives a prompt, so you have to be careful what you say around it. Lunarl is left sweating in relief that she didn’t accidentally make the robot start printing an embarrassing fanfic in front of everyone.
The humor comes from the sudden panic and near disaster of accidentally triggering an AI to publicly produce something indecent because of a stray thought.