My current favorite fantasy is where a (sweet hearted) sorority girl seduces her cute Asian besty (who grew up very sheltered), with their guy friend that they both have a crush on. The night before, Lihua got drunk with Dari (short for Darianna) and confessed that she had a crush on Greg. Then she kissed Dari and started taking her own shirt off. Dari, being a good friend, didn't want to take advantage of Lihua, so she turned her down gently, after which Lihua passed out.
But Dari is an instigator. Fill in the blanks as needed.