The OG Day the Earth Stood Still
1950's classic scifi. it's still relevant as a social commentary on MAD doctrine. The one with Keanu Reeves should get the George Lucas Holiday Special treatment.
Edit: my first time watching the Titanic was spoiled. I was in highschool at the time it came out... my crush asked me to go to it (with others.) I might have ruined things with her for pointing out that we knew how it would end.. the ship sinks. apparently, she did not know how it ended....
I also found the trio of grandmas (imagine the Golden Girls stars, but horny) sitting behind us to be vastly more entertaining. It was their fifth time watching the movie. Because they enjoyed seeing DiCaprio's neked ass.