Too many people are overlooking the idea that the OP said he (I think OP is a he)wants lines to scare off the creepy girls/guys. Most of these lines might work on the creepy girls/guys I know.
Now my way to scare them off:
Become obsessive about some part of their body, I use earlobes.
Then without warning completely change one day, become all about history/logic/math/theory.
(this should have worked by now)
If you are at your wits end of them wanting a relationship with you, look them in the eye and say it was a good time dating them, but you don?t think it is working out. Wish them luck them walk away. Dump them before the first date

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