if you do n't understand what on earth is going on 
(ROOT (SBAR (IN if) (S (NP (PRP you)) (VP (VBP do) (RB n't) (VP (VB understand) (SBAR (WHNP (WHNP (WP what)) (PP (IN on) (NP (NN earth)))) (S (VP (VBZ is) (VP (VBG going) (PRT (RP on)))))))))))
(ROOT (SBAR (IN ) (S (NP (PRP )) (VP (VBP ) (RB ) (VP (VB ) (SBAR (WHNP (WHNP (WP )) (PP (IN ) (NP (NN )))) (S (VP (VBZ ) (VP (VBG ) (PRT (RP )))))))))))