Obviously

Dood presents with a minor skin infection.

Me: Doo doo doo doo. Okay, any other medical problems?

Him: Nope.

Me: You're a generally healthy guy aside from this infection.

Him: Yup.

::Hours and hours later::

Him: Is my blood count normal?

Me: Yes, totally normal.

Him: Oh good, cause I have HIV so I was curious.

Me: ::pause:: You're HIV positive? Any other medical problems I should know about?

Him: Oh, you didn't know? I thought you all could tell that stuff.

(Oops, I appear to have forgotten my physician-x-ray-vision glasses at home).