According to Oxford Online Dictionary, the word swish means among other things:
Basketball, informal: a shot that goes through the basket without touching the backboard or rim.
It sounds like a great shot in basketball that doesn't touch anything at all.
I have just watched the Big Bang Theory, Season 8 Episode 2, and the following conversations take place.
Wolowitz: So, Penny, when's the new job start?
Penny: Next Monday.
Bernadette: Did you get a chance to look over the materials I gave you?
Penny: Uh, not yet, but I will.
Bernadette: Great. When?
Penny: I said I'll get to it.
Sheldon Cooper: I'm sensing awkwardness, am I right?
Amy Farrah Fowler: Yes.
Sheldon Cooper: Swish.
Bernadette: I don't want to be pushy, but you've never done pharmaceutical sales before. It seems like you could use this time to get a head start.
Penny: Well, the first few weeks will be all training. They'll tell me everything I need to know.
Bernadette: But imagine how impressed they'd be if you showed up already familiar with the material.
The context is Bernadette used her influence to get Penny a sales job at a pharmaceutical company and Bernadette is (kinda) insisting that Penny should read and study the materials (she gave to her) so that Penny can get familiarized with many unknown terms related with the pharmaceutical industry.
I can understand what swish means in the context using the definition of Oxford Online Dictionary I quoted at the beginning of this question. However, my questions are:
What does swish mean exactly in the context?
What is its etymology?
I read this question, What does “Swish of skirt” mean? Why is it a sexist expression?, but it doesn't answer my question.