“DFL” stands for “Dead Fucking Last.” The term “DFL” is used in running and in many other sports.
 
“DFL” has been cited in print since at least 1986, when it was used in rowing.
 
   
Sports Illustrated
June 23, 1986
Say Cheese, Wisconsin
Badger eights took both the men’s and the women’s collegiate titles
Alexander Wolff
(...)
Alas, starting to row had been the Badgers’ bugaboo all season, and Saturday was no different. After false-starting once, Wisconsin got out horrendously. Said Kathy Haberman, the Badgers’ bow oar, “We were D.F.L. off the line.” (The D stands for dead, the L for last.)
   
Google Books: rec.boats.racing
Acronym Definitions
Palmer Davis
4/30/96
In article

, .(JavaScript must be enabled to view this email address) (Luis Delgado) wrote:
>I was reading Latitude 38 and came across a few acronyms that I’m not
>familiar with.  Please define the following:
 
DFL = dead last
   
Google Groups: rec.bicycles.off-road
24hours of Canaan
.(JavaScript must be enabled to view this email address)
6/4/96
Team Dittmore, a team composed entirely of three speeds came in dead last which is total victory for them.  They beat team botulism to last placeand also team DFL (dead fucking last).  Awesome!!!
       
Beastiemania
DFL (Dead Fucking Last)
DFL became a household name among Beastie Boys fans when word got out that Adam Horovitz had played bass on their Grand Royal debut My Crazy Life (1993). Often ordered along with Luscious Jackson’s In Search of Manny, fans took a chance on Grand Royal’s first few releases and were not let down. DFL’s distinctive brand of California Hardcore earned the band a fan base that was every bit as dedicated as Luscious Jackson’s. Both bands joined the Beastie Boys on the 1994 Lollapalooza tour and proved that they were just as strong on stage as they were in the studio.
 
Google Books
Bud, Sweat, & Tees:
Rich Beem’s Walk on the Wild Side of the PGA Tour
By Alan Shipnuck
New York, NY: Simon & Schuster
2003
Pg. 268:
Though he hung up a respectable 70, Beem still finished, by three strokes, DFL — caddie parlance for Dead Fucking Last.
 
Urban Dictionary
dfl
dead fuckin last. as in a sporting event or race. or anything else you can get last in.
Frank just got a DFL at the race.
by francisco December 08, 2003
 
15 April 2007, The New Mexican (Santa Fe, NM),  “Four Santa Feans travel to South Africa for a bike race along the Western Cape” by Jon Sward, pg. E-1, col. 3:
Actually we were DFL. This was a new term to me. It stands for “dead frickin’ last.”
 
Twitter
Andre Behrens
‏@mrandre
A blog listing who finished dead last in every olympic event. http://www.mcwetboy.net/dfl/
9:31 PM - 22 Aug 2008
 
Twitter
Bernhard Warner
‏@Bernhardwarner
An Olympics tradition no more: There will be no tracker for athletes who come in DFL (dead *&^% last). http://www.mcwetboy.net/dfl/
5:29 AM - 13 Feb 2010
 
Diary of a Word Nerd
A Runner’s Lexicon
Posted on March 12, 2014 by Julia Tomiak
(...)
DFL – Dead F***in’ Last