Big bang

Oh, the squirming embarassment of it all... A friend who works away was back in town for the weekend, bringing her DVD box set of 'The Big Bang Theory' with her. 
At her suggestion the two of us sat down last night for a DVDathon with a bottle of rosé and a box of choccies. All's going well until we got to the episode called 'The Fish Guts Displacement'.
You probably know the one I mean. It hasn't gone unnoticed. If not, it's the one where Sheldon is very unhappy with Amy and decides she must be punished in some way.
The key bit goes:
 

Amy: Are you saying you want to spank me?
Sheldon: I don't want to. But, it looks like you have left me no choice.
Amy: That's true. I've been a very bad girl

The spanking gets going - see it happen here - and the smile on her face as action cuts away elsewhere tells you all you need to know about Amy's attitude to it all. I tried to make my laugh sound as normal as possible, but I'm pretty sure that the atmosphere in the room as we watched that scene was charged with something or other (Sheldon would probably know an equation to describe what was going on...).
I was certainly uncomfortable with the moment. And, I think, probably I blushed a shade of pink that matched our wine, but then felt really stupid that in a post-50 Shades world I'm still so jumpy about what makes me tick.
Is it just me? Everybody else in the spanko universe seems so relaxed about their sexuality these days, but I'm stuck firmly in my closet and would be horrified if the door were ever to open enough to let in any light.