F*ck
From Tardis Wiki, the free Doctor Who reference
F*ck was a profane word, sometimes used as a synonym for sex.
Gwen Cooper once shouted, "F*ck you!" at Jack Harkness after he taunted her for her affair with Owen Harper.(TV: End of Days)
Owen himself used the word to call a group of cannibals "sick f*ckers" (TV: Countrycide)