I don't know.. she's the female Sheldon and like him she's socially totally inept or rather very factual and scientific.
She's reads about how a slumber party is supposed to work and fails to realize that the last part with the lesbianism is more of a male teenager fantasy (it said so on the "manual"!
) so she went through with it.
I don't buy it one bit. The first time she appeared, she declared that under no circumstances would Sheldon even be allowed to touch
her. She's a character who's averse to any form of overt sexuality.