The act of taking a dump in someones Jack O'Lantern during the fall, particularly during Halloween and other harvest celebrations.
Vanessa: Gary did it! He pulled a fall classic!
James: Where did he do it?
Mike: Over on old man Jenkin's porch...
James: I'll be sure to avoid that house.
The World Series of MLB, which occurs every fall. The World Series/Fall Classic features the teams that won the American League pennant and the National League pennant. Winners of the 7 game series are World Champions.
Rick: what are you doing this evening bro?
Andy: I'm watching the Fall Classic of course.
Rick: right, who's playing this year?
Andy: Phillies & Yankees.
1) The act of taking a dump in a neighbor's jack-o-lantern on Halloween.
2) The ultimate shenanigan to pull on All Hallow's Eve. (ie. The "Fall Classic" being referred to The World Series of Major League Baseball)
1) Guy 1: Hey man. how was trick or treating?
Guy 2: Dude, it was EPIC! I pulled a Fall Classic on my grumpy neighbor
Guy 1: Niceee
2) Guy 1: That was legend! I can't believe you pulled off The Fall Classic.
Dropping a deuce in a jack-o'-lantern as a Halloween prank.
My neighbor just put out his jack-o'-lantern. Time for a Fall Classic tonight.