Okay, I'm gonna be a jerk now but I can't resist: here's your prompt filled by moi in twenty words.

Sam had a UTI. Dean gave him Azo.
His pee turned orange, Dean laughed at him, then he was fine.
The end!

Heehee.

But it's a cute idea. And something that Sam definitely wouldn't want to mention, which would make it all the better- he'd get all red in the face and be all "I'm FINE, geez" when Dean started to worry. Then Dean would buy him cranberry juice and pat him on the head. XD