The day after "Throwback Thursday," in which you don't care about people's posts on social media because you are sick of seeing pictures of douchebags from years previous.
The end of the week, and you are already mentally checked out of anything remotely having to do with work.
"I am sick of this TBT shit. I am ready to post a Fuck You Friday status telling people where they can go."
"Amy wanted me file those reports. I did right in the garbage can because it is Fuck You Friday!"