Your Step-Mother seems so uncomfortable coming into your room. She's unsure about how to talk to you right now. The glass of in her hand is obviously for her nerves, as she mentions that the dinner she had with friends threw her off a little... Sure, boys your age say things to their friends. They do things like play gay and then call their friends "faggot". She's aware, but she's not quite sure that your behavior isn't going too far.
Of course, being gay is totally fine, she assures you. However, she's worried... being gay is fine, but it will make your life much harder. For that reason, she wants to be prepared. And she needs to know where you stand, sexually. Your cock comes out as she strips, and she's watching it... She really wants to know. Are you gay?