Ever since Ferris Bueller looked out his suburban Chicago bedroom window and declared, "How could I possibly be expected to handle high school on a day like this?" his day off has been an inspiration for people trapped in offices and classrooms on those bright, sunny days when the tedium of work seems cruel and unusual. Until now, the exact date three teenagers skipped school, drove an antique Ferrari into downtown Chicago, looked at some art, went to a Cubs game, briefly united the entire city in song, and destroyed an antique Ferrari, was unknown. But thanks to some heroic statistical sleuthing by Baseball Prospectus's Larry Granillo, we know the date: June 5, 1985.

Which is why we submit that every June 5th, the anniversary of Ferris Bueller's day off, should be made a holiday: ideal for parade-crashing, spinning elaborate lies about the mortality of your girlfriend's grandfather, and, generally, stopping and looking around once in a while. 

Granillo pinpointed the date by scrutinizing some fragmented data in the film about the Chicago Cubs game being played during the gang's trip to Wrigley Field. "It appears obvious now," writes Granillo, "that this is a real ballgame that Ferris is at, not just something recreated for a film crew. The Harry Caray play-by-play and the Braves players on the field are pretty solid evidence of that. So what game, then, are they watching?" After examining the box scores of games during the Cubs 1985 schedule, he ultimately concludes that it was the June 5, 1985 game against the Atlanta Braves (the visitors won 4-2).  But he digs deeper:
More interesting than that is the timeline that this presents for Ferris. It's said in the movie that the reservation he stole was for noon, but we can't say with certainty if that's what time they ate. Seeing as how they finished the lunch with no hassles, it's safe to assume either Abe never showed up or he showed up well after their lunch was finished. Either way, with a start time of 1:25pm that afternoon, there is plenty of time for Ferris and company to make it to Wrigley in time for the game.
The eleven-inning game took 3:09 to complete, which means that the foul ball Ferris catches had to have been sometime after 4:00pm. That leaves, at the most, one hour and forty-five minutes for their trips to the museum, Sears Tower, the lake, and Sloane's house, while squeezing in two musical numbers during the parade before racing home at 5:55pm. Seems a bit tough to squeeze all of that in for most normal people. But, seeing as Ferris has the magical ability to sound exactly like both a young Wayne Newton and a young John Lennon, I'm willing to believe he could make the schedule work.
Like how we'll all make it work, come June 5.