The Brief: WTF stands for "What the f**k?"
WTF stands for “What the f**k?” It is an acronym used primarily in texting or instant messaging, though much like LOL and ROTFL millennials and Gen Zers have been known to say the letters aloud. Rather than exclaim, “What the f**k?!” one might say, “WTF?!” or even “What the Eff?”
Sometimes, WTF is used to express anger or outrage (often followed with a question mark or exclamation point):
OKokokokok So, disregard my last tweet? Fedex said 'delivered Jan 10th' so we all thought it got stolen, but somehow it was actually SENT BACK TO THE TROPHY MAKER WTF. So, Humanity is still intact, mother shucker!#MakeMomHappyIn3Words: Trophy Got Returned pic.twitter.com/lIYwtldp5M
— Melanie People’sChoice Scrofano (@MelanieScrofano) January 28, 2019
WTF can also be used as to indicate excitement or surprise:
— Jaclyn Hill (@Jaclynhill) January 29, 2019
In any case, WTF is best expressed in all capital letters for full effect.