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Nightmare Fuel: Freddy vs. Jason
Lori's "Please wake me up!".
And a little later in her dream where Freddy basically tries to rape her...sliding his finger blade up her leg in a sadistic and perverted manner and pulling her skirt up... revealing her bare legs as she's whimpering.
Mark's nightmare is probably the scariest scene in the film. He quickly realizes exactly what's going to happen and that there is absolutely nothing he can do about it.
"Somebody please wake me up! Please!"
Freddy Krueger's past is laid out in a prologue that features an offscreen murder of a little girl — who's later seen in a dream sequence with her eyes cut out. Say what you want about Freddy's Villain Decay, but he got his reputation for a reason.
Basically, that was the scene that instantly reversed two-decades of Villain Decay for Freddy: even with the stupid gags, even with the lame jokes, he kills children for fun.
There's also the way he slowly licks her photo before pasting it in a book filled with newspaper articles about missing kids in Springwood and photos of all the kids he's killed. It's quietly terrifying and leaves you feeling fouled just by seeing it.
Freddy's torment of a young Jason after their Dream World fight is horrific — especially considering Jason is a little boy and Freddy is a child murderer.
Kia lampshades the nightmare of having to deal with both Freddy (who attacks in dreams) and Jason (who attacks in reality) with one line: "We're not safe, awake or asleep!"
There's something mildly disturbing in seeing Jason come back to life. You get a close up of his open chest cavity, with discolored bones and decaying organs that have vines growing through them. And that excuse for a heart starts pumping.