New answers tagged spoken-language
そういうこと in the first dialog corresponds to the second meaning: 「前述の発言内容を全面的に肯定する」. This そういうこと refers to the "lesson" which 音ちゃん just realized (自慢しちゃダメ). This kind of そういうこと can be translated as "Now you understand it", "Yeah, that's what I mean", etc. (Strictly speaking, in this case, 音ちゃん had not explicitly said something like 自慢しちゃダメだった when he said ...
It's the girl who is showing her 包容力 (to her boyfriend). 彼氏くんの方が攻め攻め implies the boyfriend was aggressive and taking initiative, and the girl was acting rather passively. But in reality, the girl was not that passive, but was intentionally letting him do as he likes (with her "broad-mindedness" ≒ 包容力).
I think ブームメント can be either a simple malapromism, or an intended neology combining "boom" and "ment" of "movement." It may mean a sensational boom, but I'm not sure. The word, ブームメント isn't a standard Japanese word anyway.
I believe ブームメント is simply a typo. Some people seem to have mixed ブーム (boom) with ムーブメント (movement) and came up with ブームメント. Watch this video, where one idol accidentally said ブームメント, and was corrected by others at once. https://youtu.be/Hl8V6vtdYIc?t=35s
Regarding your quote,「ったく、銀貨５枚とどちらが割に合うんだかな」, "ったく" doesn't make sense in Japanese. Is it "全く"？ Something is missing. "どちらが割に合うんだかな" means "Which would be worth more?" or "Which is more advantageous (profitable)?" A more common way of saying this is "どちらが割に合うのかな" or "どちらが割に合うの（ん）だか." I think "な" at the tail is used for the purpose of emphasis or ...
To use your words. I think it is something like "I wonder what is/would be more worth it, those 5 silver coins that boy offered, or this 'free' meal I will receive. Clearly dissatisfied with the the reward he will receive, which is presumably, worth less and the request will be more troublesome if he has to look after this other person as well.
The sentence means "I can't tell you only once or twice. I want to tell you more.".
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