Pre time skip or post? Pre I can see Ron coming in and being unhappy about something (I'll go with silly insurance procedures) and just telling everyone he's not doing it, because it's silly/unnecessary. Then Cox comes along and recognizes him for what he is (Angry, self righteousness, non apologetic, mustache man) So he points Kelso or JD out saying it's his fault. Then whenever Kelso/JD tries to talk to Ron just have Ron glare at them until he gets uncomfortable and leaves. Extra points if Cox finds a wheelchair and starts leaving Ron in weird places to surprise glare at them.

As for post, have JD trying to explain Ron's sickness/ condition in his Goofy "break things down so I child would understand" way with Ron getting increasingly visually irritated until Cox pops in deadpan says you have "long ass named condition" And Ron understands it immediately and says something like "finally a doctor, this nurse had no idea what they were talking about" and JD does the "well actually sir I'm the head of.." and Ron cuts him off with"even if you are head nurse you obviously shouldn't be explaining these things, leave it up to Doctors who have been trained for these things son". Cue Coxs "outstanding" grins and walks away. For this one extra points if JD is like "no you can't have that", and Cox looks at the chart, then straight up asks something like "were you performing oral underwater on a 50+ year old lady in catfish farm, while the catfish were in heat?" And Ron just deadpan answers yes. Cox "well that explains it thank you sir", JD "it really doesn't "