The World Taekwondo Federation.
WTF, holds many competitions throughout the world.

Generally stands for 'What the fuck'. Most people use a question mark afterwards to get the point through. Rather than using the same term for the other 'w's, who, when, where, and why, it makes more sense to actually state the word and follow it with 'tf'

Capitalization doesn't really matter.
This term can also be likened to 'What the shit?' which is more comical and has a tantamount meaning.

1. What the fuck.
2. World Tae Kwon Do Federation

The universal interrogative particle.

The abbreviation of, most commonly, 'what the fuck', though sometimes also 'who/why/when/where the fuck'. When used with an exclamation point instead of a question mark, it becomes an exclamation of amazement, confusion, disbelief, ect.

Both forms are often accentuated with 'mate' or preceded by 'dude'.

What one would say if some dude wearing tight pink clothes and roller skates was sitting on a bench on 42nd street in the middle of New York.

An overly used internet acroynm said to mean 'what the fuck'. Fun to say around old people.

WTF usually refers to 'what the fuck'. It can be used as a question, an exclamation, and many other uses.

It is commonly used in internet chatrooms where swearing is censored.

The 'W' can be used as what, where, who or when, following by the 'TF' which is always 'the fuck'

WTF is usually used with dude or mate