A few ideas for the movie they could be watching:
EVERY Awkward scene from AotC. They could comment on how awful it is.
Every scene from the OT where Luke and Leia are flirting, making out, etc, followed by the "Leia is my sister" scene, then Han asks, "You love him, don't you" and she says "Yes." This is followed by a string of NOOOOOOOOs from the saga.
Or they could just watch the "I am your father" reveal from Empire.