I think this one wasn't translated because of the weird ザクーッ (zaku-) in there.
It seems to be an onomatopoeia, as we can see from it being present in the background of the next panel (post #3146315) in this series. In the context of that panel, it seems like it's the sound of, well, insertion.
In the pixiv comments, there's also a comment about this: "エロ漫画を読み始めてかれこれ15年になるが、挿入の音が「ザクゥ」なんていうエロ漫画初めて見たぞw"
Which I'd translate as "I've read hentai for about 15 years, and this is the first time I've seen 'ザクゥ' as the insertion sound lol"
So that commenter took it to mean "stick it in", and in context that makes more sense than anything else really.
I put in that interpretation as the translation, if anyone knows better, feel free to leave a comment and fix it!
I think this one wasn't translated because of the weird ザクーッ (zaku-) in there.
It seems to be an onomatopoeia, as we can see from it being present in the background of the next panel (post #3146315) in this series. In the context of that panel, it seems like it's the sound of, well, insertion.
In the pixiv comments, there's also a comment about this: "エロ漫画を読み始めてかれこれ15年になるが、挿入の音が「ザクゥ」なんていうエロ漫画初めて見たぞw"
Which I'd translate as "I've read hentai for about 15 years, and this is the first time I've seen 'ザクゥ' as the insertion sound lol"
So that commenter took it to mean "stick it in", and in context that makes more sense than anything else really.
I put in that interpretation as the translation, if anyone knows better, feel free to leave a comment and fix it!
"Zaku" (and variants) is the onomatopoeia for a very deep, forceful *STAB*. It is certainly unusual to see it as the SFX for "jam PONOS into VAGOOO".
(And yes, said onomatopoeia is also the namesake for the Gundam MS, adding to the hilarity.)
Edit: Also, the ひと思いに is actually 一思いに (not 人...).