#Edit: Holy moly so many people already offered to write a fic

[i-actually-found-jericho]

Both RK800 and RK900 adapt behavior from their environment, right? That includes speech. So instead of being like "??????" whenever Gavin uses slang from his youth, Nines picks the phrases up and remembers them along with the context. As soon Gavin realizes this, he keeps making his sentences more ridiculous. It works. 

Because the next time they have to interrogate someone, RK900 opens the conversation in all seriousness with "Are you ready to spill the tea or are you gonna stay salty this whole time?"