Kathy,
How this time has flown and within days, you'll be on the other side, slowly getting your life back. How wonderful for you.
Unfortunately, no one will actully see your green undies, thong or otherwise. They'll give you a bag and a gown, then tell you to go into the bathroom, take off all your clothes, put them in the bag and put on the latest fashion of a hospital gown. So the green undies may cheer you up but will only give everyone else a boost if you tell them about it so make sure you mention how you dressed for their enjoyment
I think the worst part of a surgical experience (aside from post op pain) is the IV. I always ask for lidocaine first and then let them poke away. The happy juice comes next and then good night. Don't fret it.
Good luck and happy thoughts, Dale