As always, the mangaka poses to us a very difficult philosophical question - what truly is "a fuck"? Sure; we could immediately go to a sexual or pejorative meaning, (as fits common usage of the word, of course) but we could also ask about the nature of the question. Perhaps we are looking at a simple miscommunicatiom, a difference in language perhaps, but do we think about the actual meaning of "the fuck" in question? Deep stuff.