doing unpleasant things to each other and themselves 
(ROOT (S (VP (VBG doing) (NP (JJ unpleasant) (NNS things)) (PP (IN to) (NP (NP (DT each) (JJ other)) (CC and) (NP (PRP themselves)))))))
(ROOT (S (VP (VBG ) (NP (JJ ) (NNS )) (PP (IN ) (NP (NP (DT ) (JJ )) (CC ) (NP (PRP )))))))