naff

Concise Oxford English Dictionary © 2008 Oxford University Press:
naff1

▶verb Brit. informal

• 1 (naff off) go away.

• 2 (as adj. naffing) used to emphasize annoyance.

– origin 1950s: euphemism for fuck; cf. eff.

Concise Oxford English Dictionary © 2008 Oxford University Press:
naff2

▶adjective Brit. informal lacking taste or style.

– derivatives
naffness noun.

– origin 1960s: perh. from Polari.