Some scenarios from work:
Seeing a patient I've known for years with Kallmann syndrome and anosmia.
Me: "Do you have any sense of smell?"
Patient: "No. Why?"
Me: "Good. I just farted."
Me, teaching the resident physician about Addison's disease and hyperpigmentation (from the ACTH stimulation), and how to look for tan lines to distinguish between pathologic skin color changes versus from UV exposure.
Resident: "What if the patient uses a tanning bed in the nude?"
The right answer would have been to look at the buccal mucosa. Instead, what I told him: "You could spread the buttcheeks out a bit to see if the covered areas are hyperpigmented."
My nurses who knew I was kidding, just exploded.
And they say we can't have fun at work.