I've been meaning to do a thread on this for a while now, but it's finally time I talk about my greatest shame and perhaps most difficult localization experience I've ever had - the Yakuza 6 LIVECHAT. 
For those who don't know, there's a substory pretty early on that takes Kiryu to an internet cafe with a strange man obsessed with chatting to girls online. Upon clearing this substory, you get the option to come back and enter the brave new world of livechat via minigame.
To type to the girls, Kiryu has to click clack away at an individual button for each letter, spelling out words or phrases in the process. These get progressively more... risqué as time goes on, but it's still pure old Kiryu deep down.
The interesting thing about these messages, though, is that every facet of them had to be changed for our English release. How long the word is, how much time you have, which buttons you press. But in doing so we tried to implement a logic to it.
A space would always be triangle, a question mark would always be square, etc. But there was even more to it than that. We had to make sure it felt "rhythmically" right (basically that it felt good), and that the buttons themselves corresponded to the letters Kiryu typed.
This is to say nothing of the chat window constantly scrolling on the side of the screen, with such upstanding citizens as Sexbot9000, comin4booty, divorced7times, and many, many more. This is where it really got fun.
Usually we try to avoid memes and references in our titles, but this is one place it felt wildly appropriate. The people in the chat use Lenny faces (we had to fight tooth and nail to get this in the game), they toss around boob emojis, they make anime references and dumb jokes.
But one of the most interesting parts was giving them each their own "character". This was a little different than regular characterization, and involved making each person type a certain way, with different styles, levels of joking, amounts of typos, capitalizations, etc.
In the end, I think I ended up watching those videos for 2 weeks straight trying to get every little detail just right, and even now I remember those scenes like the back of my hand. Anyway, none of this would have been possible without some all-star translations from @qrefrain!
