"If you people only knew how fatally easy it is to poison some one by mistake, you wouldn't joke about it. 
( `` ( ( If ( ( you people ) ( only ( knew ( ( how ( fatally easy ) ) ( it ( ( is ( to poison ) ) ( ( some one ) ( by mistake ) ) ) ) ) ) ) ) ) ( , ( you ( ( ( would n't ) ( joke ( about it ) ) ) . ) ) ) ) )
(ROOT (S (`` ``) (SBAR (IN If) (S (NP (PRP you) (NNS people)) (ADVP (RB only)) (VP (VBD knew) (SBAR (WHADVP (WRB how) (ADJP (RB fatally) (JJ easy))) (S (NP (PRP it)) (VP (VBZ is) (PP (TO to) (NP (NN poison))) (NP (NP (DT some) (NN one)) (PP (IN by) (NP (NN mistake)))))))))) (, ,) (NP (PRP you)) (VP (MD would) (RB n't) (VP (VB joke) (PP (IN about) (NP (PRP it))))) (. .)))
You wouldn't joke about poisoning someone if you knew how easy it was to do by mistake.
( You ( ( ( would n't ) ( ( joke ( about ( poisoning someone ) ) ) ( if ( you ( knew ( ( how easy ) ( it ( was ( to ( do ( by mistake ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP You)) (VP (MD would) (RB n't) (VP (VB joke) (PP (IN about) (NP (NN poisoning) (NN someone))) (SBAR (IN if) (S (NP (PRP you)) (VP (VBD knew) (SBAR (WHADVP (WRB how) (ADJP (JJ easy))) (S (NP (PRP it)) (VP (VBD was) (S (VP (TO to) (VP (VB do) (PP (IN by) (NP (NN mistake)))))))))))))) (. .)))