is hitting your head on the theater seat in front of you when you doze off thirty minutes into the film . 
(ROOT (S (VP (VBZ is) (S (VP (VBG hitting) (NP (PRP$ your) (NN head)) (PP (IN on) (NP (NP (DT the) (NN theater) (NN seat)) (PP (IN in) (NP (NP (NN front)) (PP (IN of) (NP (PRP you))))))) (SBAR (WHADVP (WRB when)) (S (NP (PRP you)) (VP (VBP doze) (PRT (RP off)) (NP (NP (CD thirty) (NNS minutes)) (PP (IN into) (NP (DT the) (NN film)))))))))) (. .)))
(ROOT (S (VP (VBZ ) (S (VP (VBG ) (NP (PRP$ ) (NN )) (PP (IN ) (NP (NP (DT ) (NN ) (NN )) (PP (IN ) (NP (NP (NN )) (PP (IN ) (NP (PRP ))))))) (SBAR (WHADVP (WRB )) (S (NP (PRP )) (VP (VBP ) (PRT (RP )) (NP (NP (CD ) (NNS )) (PP (IN ) (NP (DT ) (NN )))))))))) (. )))