Search Results: flirting or just being funny

I'm a nurse, and at my hospital, we have medical students come around every so often, accompanying some of the Doctors. There are two guys that always seem to be together, and sometimes they visit my ward.
I remember the first time I met them, they seemed a bit lost, so I helped them out, which they seemed to appreciate. I've seen them a couple of times since then, and they always seem to target me, rather than any other nurses if they need help with something. Like if they see me sitting at the desk, they'll zoom up to me and tell me they need my help.
One of them seems particularly more friendly with me than the other one, and sometimes he tries to strike a bit of conversation with me, like he'll point out something that is funny, or will tell me that the Doctor they're paired up with is quite frightening.
The other morning, they were all crowded around the Doctor while she was teaching them something, and the friendly medical student turned and looked at me when I walked past, and gave me a big smile. I'm not sure if he is just a friendly person or not, but I hope he's slightly interested, because I kind of like him.
The problem is, I don't know how long they're going to be in the hospital for, for all I know, they may have finished their prac already. And I never know when they're coming back. It's also hard to find opportunities to talk to them, as they're most often with a Doctor, being taught something, or I'm just flat out busy and unable to talk.
But I really don't want to miss out on this opportunity, as he seems like a lovely guy.
I'm afraid to just straight out ask for his number or something, as it may seem to be a bit abrupt and out of no where, as we havn't spoken THAT much, plus if he really isn't interested, I don't want it getting back to the Doctors, and have them thinking that I'm.just some flirt, because I'm not.
Is there something I can do, to show some interest, which will open the opportunity for him to ask for my number?