It does seem like one could make a plausible case that Office Space has had the biggest impact on real world life of any movie of all time. Just skimming down the list, it doesn't look like there's anything on the AFI or BFI top 100 even comes close. Maybe 12 angry men has had a real influence on juries in some unseen way, or maybe The Social Network has also had a big influence on what careers people choose, but there's nothing that immediately seems super obvious as surpassing it.