As you wanted to stop it, it was to late, you realize that you have to fake some story now. This bothers you, because you are really an boy and you don't like seeing yourself like this.
You are not having fun, and don't really want everything to end abruptly.
So you are trying to pretend to be Dave’s ( your own!) cousin. But you get to realize that this guy is not really believing you. But it was not an option now to tell him the truth.
But your body is tall, pretty, you have strawberry-blonde long hair and are a girl in her late teens. You don't know anything about her life, but you figure it would be fun