of gags that rely on the strength of their own cleverness 
(ROOT (PP (IN of) (NP (NP (NNS gags)) (SBAR (WHNP (WDT that)) (S (VP (VBP rely) (PP (IN on) (NP (NP (DT the) (NN strength)) (PP (IN of) (NP (PRP$ their) (JJ own) (NN cleverness)))))))))))
(ROOT (PP (IN ) (NP (NP (NNS )) (SBAR (WHNP (WDT )) (S (VP (VBP ) (PP (IN ) (NP (NP (DT ) (NN )) (PP (IN ) (NP (PRP$ ) (JJ ) (NN )))))))))))