John: So, do you have a girlfriend who feeds you up sometimes?
Sherlock: Is that what girlfriends do? Feed you up?
John: You don't have a girlfriend then?
Sherlock: It's not really my area.
John: Oh. Right... Do you have a boyfriend? (Awkward pause) Which is fine by the way.
Sherlock: I know it's fine.
John: So you don't have a boyfriend then?
Sherlock: No.
John: Right. Okay... So unattached, like me. Good.
Sherlock: John, you should know I consider myself married to my work and, while I'm flattered by your interest, I'm really not looking for any kind of...
John: No. No. I wasn't asking you out. No. I'm just saying it's all...fine. Whatever shakes your...boat - I'm gonna shut up now.
Sherlock: I think that's for the best.