What did I just watch?

Is there any grammatical mistakes in the above statement?

What are some of the worst movies you’ve watched?

Is that true? If you have heard someone say this, they propably said:

WTF, I just watched….

Using WTF as an interjection, then describing the cause of their distress. I can watch some sports, and exclaim: WTF, I just watched

that player cheat!

How do I know if a player has broken a rule and not get penalized?

Can a non-question call “WTF” at the end of an answer? Can “WTF” be added as a non-question? If “WTF” is used as an exclaimation/interjection followed by a non-question (as in my sports example), it is grammatically correct.