F*ck

Fuck was a profane word, sometimes used as a synonym for sex.

The word was used in the expressions "what the fuck?" (TV: Everything Changes, Countrycide) and "fuck knows", (TV: Random Shoes, End of Days) and the terms "fucker" (TV: Countrycide) and "fuck buddy". (TV: Out of Time)

Gwen Cooper once shouted, "Fuck you!" at Jack Harkness after he taunted her for her affair with Owen Harper. (TV: End of Days)

Owen used the word to call a group of cannibals "sick fuckers". (TV: Countrycide)