It's slang for "Ignore them" or "Forget what they said" or "Don't take any notice" or several other things depending on context.
- I want to go to Pizza Hut for lunch.
- So do I, but all our friends are going to McDonalds for lunch.
- Screw those guys! If we want to go to Pizza Hut then we will. They can go wherever they like.
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