What is 4xfat?
The 4xfat is a heat of the 4x100m relay, in highschool and sometimes college, run by the throwers on the track team. The 'fat' in 4xfat is due to the bulky stature of a typical thrower when compared with a sprinter.
Sprinter #1: The 4xfat was pretty fast today.
Sprinter #2: Tru.