Frequent Stinky Gas
In our 6 months of pre-op classes we were warned about this problem by our teachers, and it was confirmed by the post-op speakers that would come and talk to our classroom. It was the standing joke that we should all by stock in Glade Air Fresheners before going to the operating room. I don't remember if they told us why this would happen, though, just that you could count on it.
I'm 5 months out and up until about 2 weeks ago I could proudly state that my "S" don't stink! Seriously - it was completely odorless.
But now... I believe the dreaded prophecy is starting to come true. (When your dog faints after walking by the bathroom, you know you're in trouble.)