One time when my sister was in high school and I was home from college for some reason or other, I tricked her into going to see David Cronenberg's The Fly. That really didn't go over so well; it's really not her type of movie, since there isn't a princess or a maid of honor in it and it doesn't end at a prom. Anyway, the audience was really nervous and fidgety and there were a lot of funny comments from frightened audience members that served to break the tension. All of which crescendoed when Geena Davis had that dream sequence where she gives birth to that giant fly larvae baby thing and the woman behind us said as clearly and loudly as possible, "I don't know why she don't get a can of Raid and put a STOP to that shit!" So even though today's How To advises against talking in movies, you're allowed to if you can be that funny.
I also tricked my sister another time when I made her ride a carnival ride where you twirled upside down and then stopped upside-down in mid-air and her purse flew open. I'll save that one for another time (How to Go to the State Fair...coming in September) but let's just say that the lady carny way way below us got a bunch of free birth control pills. Which from the looks of things, she was probably going to need later that night.
Thanks to world-famous authoress Katharine Weber for suggesting this one.