I might be wrong, but Joyce wrote some of the most sexually explicit letters that you can imagine, to his wife, and those ended up published in a book a while ago. What I'm trying to say is, maybe Andy caught his sis pleasuring herself while reading that book? The sexuality of those letters is very stimulating, as it's written in very poetic, colorful language :).
I might be wrong, but Joyce wrote some of the most sexually explicit letters that you can imagine, to his wife, and those ended up published in a book a while ago. What I'm trying to say is, maybe Andy caught his sis pleasuring herself while reading that book? The sexuality of those letters is very stimulating, as it's written in very poetic, colorful language :).