I can't stop watching this.
In case you were wondering, this isn't canon. What's going on here is a common mod trick of replacing a character model with another one. Weird enough when you're swapping out one human being for another, but nightmarish when you throw animals into the mix. In this case, someone's swapped out D-dog for Revolver Ocelot.
To be fair, I'd rather Ocelot humped my leg than a dog did.
Speaking of Ocelot, have you heard of the Hawkeye Initiative? It involves artists drawing Hawkeye—and occasionally other male characters—in poses usually reserved for female characters in comic books and movie posters and the like, in order to shake up our ingrained cultural misogyny and demonstrate how ridiculous these poses are.
It turns out model-swapping mods make for a great video-game version:
Credit to Kotaku for spotting this one, which has Ocelot stand in for Quiet this time. Watch the original, named by its uploader the "Best Quiet Scene", if you can't believe that such a scene exists. Alternatively, see what it would be like if Quiet were a dog.
Of course, you could also use model-swapping mods to swap out Snake, maybe so that you can play as Quiet, though I can't find a video of that that doesn't involve zooming in on her boobs so you'll just have to try it for yourself.
Want to give model-swapping a go? Nexus Mods has a tool for that. Don't forget to back up your data first.