Being too exhausted on Friday due the rest of the week to go out and have fun, or do anything other than sleep. A serious condition any place where employees or students are worked to the bone.
Suzy: Hey May, our finals are finally over! Its Friday, lets go out and celebrate.
May: I really want to, but I'm running on 4 hours of sleep, I won't be able to make it.
May has Friday fatigue.
Bill: Bob, you won your first case! Lets go out and celebrate, its Friday!
Bob: I've been too stressed out to sleep all week, I think I'm just going to stay in tonight.
Bob has Friday fatigue.