WARNING: The following contains spoilers for Boruto: Naruto Next Generations Episode 194, "The Uzumaki Household," now streaming on Crunchyroll.
In the Boruto series, Naruto has usually tempered his thoughts when it comes to Boruto. He can relate to the rash, impetuous kid as Naruto was the same way when he was a teen. He knows that, in time, his son will mature and realize what Konoha needs from him.
It helps that Naruto is far more patient and knows not to stress out, as he's already got plenty on his plate as Hokage of the Hidden Leaf. However, in Episode 194, we discover what he really thinks of the boy -- and it definitely leaves him a tad worried about Boruto's ability to read the room.
Naruto is facing an uphill challenge as Boruto and Kawaki aren't getting along after the latter was adopted. From fights at the dinner table to squabbles about toilet sharing, they're always at each other's throats. Still, Naruto makes it abundantly clear that they're family now and must work together. It's the only way they can help figure out how to save Kawaki from the dark destiny the terrorists had in mind for him.
It culminates in Kawaki entering Boruto's room and holding a heart-to-heart. This is rare as he's usually so closed off, putting up walls because Jigen and Kara taught him that vulnerability, emotion and sentiment are all weaknesses. He discusses his Karma mark with Boruto, inquiring about how Boruto got his own. When he hears it's from the Momoshiki fight, Kawaki is stunned as it's totally different from his.
Thus, Kawaki details Jigen's sadistic experiments, which Naruto has tried unsuccessfully to pry out of him since they met. Luckily, Naruto is eavesdropping as he hears about the other guinea pigs and the process itself at the Kara lab. He needs info for Shikamaru and the other leaders in the alliance, as well as his own science team. But just when Kawaki gets into it and Boruto finally warms to the idea of working together, a mix of awkwardness, nervousness and anger sets in. Naruto's son switches the topic to Kawaki breaking Himawari's vase from a few days ago.
It's clear Boruto doesn't know how to handle the concept of a brother, and so he botches the conversation. Kawaki immediately speeches him off, breaking his train of thought and as Boruto exits, Naruto facepalms and whispers to himself, "That idiot!"
Naruto knows being a shinobi requires tact, timing and temperament, but his son has little of these. It's just as much a mental game as it is physical, so this hits his expectations for the prodigy he sired. It also leaves Naruto worried that Kawaki still doesn't trust them, and more so, that he might not open up like this again due to his insecurities about families betraying him.