Prove to me you are not gay please

It is time for you and your stepsister to have a heart-to-heart talk now that you are 18. Cassandra wonders if you might be gay. Maybe you are bi instead? She just wants to know because she thinks that you have been checking out her boyfriend, so she wants you to prove to her that you can get hard for a girl. She shows you her perky, puffy tits and your dick starts to get hard. Cassandra is pleased that you have gotten hard in response to her pretty tits, but the real test is whether you can cum for her. She lifts up her skirt and you see she is wearing no panties. Her hair is also shaved into a little triangle. You have only seen pussies in porn, so seeing one in person has your dick throbbing. Those thigh-high socks she wears are oddly appealing to you.