What is the meaning of The_fuck?

Used with an interrogative pronoun as an intensifier to express anger, frustration, incredulity, or other strong emotion.

Used after verbs forming a part of a phrasal verb as an intensifier to imply aggressive emphasis.

Used as a shortened form of the common interrogative phrases.

Used to emphatically express that something isn't true.

Used to emphasize an adjective; fucking.

Source: wiktionary.org