you laugh once ( maybe twice ) 
(ROOT (S (NP (PRP you)) (VP (VBP laugh) (ADVP (ADVP (RB once)) (-LRB- -LRB-) (RB maybe) (ADVP (RB twice)) (-RRB- -RRB-)))))
(ROOT (S (NP (PRP )) (VP (VBP ) (ADVP (ADVP (RB )) (-LRB- ) (RB ) (ADVP (RB )) (-RRB- )))))