Harry Cassandra thought he was being "casually witty" when he suggested "nibbles" to a woman. (The fact that he shouldn't have been pursuing her in the first place is not relevant to this analysis.)

Haus Frau explains the effect that being "casually witty" has on women:
Cutesy crap and try-hard witty snark are both kryptonite. Cutesy is far less tolerable between the two. My husband used to baby talk to me when teasing. As in I would be playing with one of the kids or mention something they did and he would go into the baby talk voice "aaaw momma loves the little babies..." and this would just go on.

I quietly told him more than once to stop doing that habit but it just didn't seem to register with him that I really meant it. One evening after he indulged in a few drinks he kept doing the baby talk thing and I basically verbally snapped his head off. He was hurt. I felt bad and apologized. It was bad. He really didn't get how white hot pissed that habit made me.......the moral of the long-winded anecdote being that repeated cutesy shit like using the word "nibbles" for snacks creates such a level of seething irritation that you might as well have sewn up her vagina with a bear trap.
The reason is pretty simple. Men use "casual wit" in order to verbally sidle up to women. They do so in order to talk around their intentions and thereby avoid risking the sting of rejection that being straightforward entails. It's all very cowardly and feminine, which is precisely why it arouses such contempt in a woman.

All men are capable of making this mistake, but Gammas are particularly prone to it because they live in a near-constant state of delusion concerning their ability to fool everyone about their real feelings and intentions. What they don't realize is that they pull their slick moves off about as convincingly as the bug wearing the skin of a man in Men in Black managed to mimic normal human behavior. It doesn't matter if you were "playing a role" or not, she still rejected YOU. Yes, you. Deal with it.

Women are extraordinarily sensitive to male cowardice, risk avoidance, and fear of rejection. They even subject men they have already accepted to regular tests in order to smoke it out. They sniff out male weakness and insecurity like a shark scents blood in the water. So, as a general rule, if you think you're being cleverly casual, know that it's not hiding anything. It's better to just be succinct and straightforward, and accept her response with taciturn grace no matter what it is.