That couldn't happen in a sane world, either.
( That ( ( ( could n't ) ( ( ( happen ( in ( a ( sane world ) ) ) ) , ) either ) ) . ) )
(ROOT (S (NP (DT That)) (VP (MD could) (RB n't) (VP (VB happen) (PP (IN in) (NP (DT a) (JJ sane) (NN world))) (, ,) (ADVP (RB either)))) (. .)))
That could not happen in a world that wasn't insane, either.
( That ( ( ( could not ) ( ( ( happen ( in ( ( a world ) ( that ( ( was n't ) insane ) ) ) ) ) , ) either ) ) . ) )
(ROOT (S (NP (DT That)) (VP (MD could) (RB not) (VP (VB happen) (PP (IN in) (NP (NP (DT a) (NN world)) (SBAR (WHNP (WDT that)) (S (VP (VBD was) (RB n't) (ADJP (JJ insane))))))) (, ,) (ADVP (RB either)))) (. .)))