you think you "know"

Today while on the bus, I was doing my usual activity, listening to other people's conversations.  The girl a on the seat adjacent to mine was talking to her friend a couple of seats up.   They were talking about the latter girls job.  She works at a hospital and was hoping that on game day they didn't have any "codes".  The first girl asked what that was and her friend told started explaining.  In mid-sentence the first girl stopped her 

"Oh ya, I watch Grey's Anatomy, 

I know a about medicine"

WHAT?

Seriously?

Since then, I've been thinking about what sort of things that I "know" (according to that standard).  My list:

• I "know" about piano becasue I've watched Paul practice before.
• I "know" how to be a crime scene investigator because I used to rigorously watch CSI and all of its spawn weekly.
• I "know" how to build a house because several were constructed along the highway and I would see their progress daily.

WHAT SORT OF THINGS DO YOU "KNOW"?