a sense-of-humour failure 
(ROOT (NP (DT a) (NML (NML (NN sense)) (HYPH -) (PP (IN of) (HYPH -) (NP (NN humour)))) (NN failure)))
(ROOT (NP (DT ) (NML (NML (NN )) (HYPH ) (PP (IN ) (HYPH ) (NP (NN )))) (NN )))