Just before this, the guy grabs the blade of the knife and pulls it out, cutting his palm. He tastes the blood on his hand and then wants her to taste it too. I’m pretty sure the only reason she does it is because he’s always threatening to kill her if she doesn’t do what he wants. And then he also killed her ex-boyfriend while she was having sex with him (ex). 

now look what happened to you 

what the fuck

Clint Howard is sporting some major Beavis hair in this movie