Porn would be the obvious answer but no that’s not it. In a story in Askmen.com it turns out men get turned off watching romantic comedies but history documentaries put them in the mood.
A study of men and women exposed them to various movie clips. While women were turned on by scenes from romantic films, the same clips had the opposite effect on men. They both watched clips from Titanic and Indecent Proposal, a movie of a couple having sex, and a documentary on English history. Women were most turned-on after watching the romantic movie clips, surprisingly, men were actually more turned on by the documentary clip than the romantic movie clips.
The results suggest that watching a romantic movie can actually actively decrease sexual desire in men. So maybe Friday night might I suggest Glorious Triumphs and Great Tragedies over Love Actually.