Fluffy addek humor, because I wanted to backstory something here...
What?
"What?"
"Nothing."
"You've been looking at me all day. What?"
"Is it okay to just look at my girlfriend at work?"
"Not when you look like a rabid dog."
"Oh, that's nice. How do you know what a rabid dog looks like?"
"I've seen you, haven't I?"
"Uh huh. You're insane, you know that?"
"Kesey would've had a field day."
"What if I wore blue? Does blue make me look like a rabid dog, or is it just the red shirt?"
"What?"
"The red shirt."
"It looks fine."
"Yeah, but people get concussions and say they're fine."
"Derek, do you have a concussion?"
"No."
"Would you like one?"
Reference: Kesey wrote One Flew Over the Cuckoo's Nest. Crazy people are his thing. It's a pretty good book.
I backstoried Derek's thing about his red shirt (remember season 1 when he was still going after Meredith?)