A Rube Goldberg Zipper-Zipping Machine

Since the late 1980s, Purdue University has invited students to make Rube Goldberg machines accomplishing simple tasks in absurdly complex ways. Each machine has to occupy at least a 6-foot cube, perform at least 20 steps, and achieve a stupidly simple task. This year the winners made a charmingly goofy machine to zip a zipper. Here they are walking us through the process (the action starts around 3:05):
This may leave you wondering what YKK stands for. Find it and many others in our list of 56 Acronyms and Initials All Spelled Out.
And according to Wikipedia, here's the list of previous tasks set out for the Purdue contest:
2014 Zip a zipper
2013 Hammer a nail
2012 Inflate a balloon and pop it
2011 Water a Plant
2010 Dispense an Appropriate Amount of Hand Sanitizer into a Hand
2009 LittleBigPlanet Contraption Challenge 6
2009 Replace an Incandescent Light Bulb with a More Energy Efficient Light Emitting Design
2008 Assemble a Hamburger
2007 Squeeze the Juice from an Orange
2006 Shred 5 Sheets of Paper
2005 Change Batteries and Turn on a 2-battery Flashlight
2004 Select, Mark and Cast an Election Ballot
2003 Select, Crush and Recycle an Empty Soft Drink Can
2002 Select, Raise and Wave a U.S. Flag
2001 Select, Clean and Peel an Apple
2000 Fill and Seal a Time Capsule with 20th-century Inventions
1999 Set a Golf Tee and Tee Up a Golf Ball
1998 Shut Off An Alarm Clock
1997 Insert and Then Play a CD Disc
1996 Put Coins in a Bank
1995 Turn on a Radio
1994 Make Cup of Coffee
1993 Screw a Light Bulb into a Socket
1992 Unlock a Combination Padlock
1991 Toast a Slice of Bread
1990 Put the Lid on a Ball Jar
1989 Sharpen a Pencil
1988 Adhere a Stamp to a Letter
1987 Put Toothpaste on a Toothbrush
(Via Devour.)