There is an urban legend making the rounds currently about this old Malay woman who goes from door to door selling keropok. If you refuse to buy from her, she will unlease her pet Ms P on you. Another version is that she will ask to rest in your house and if you let her in, she will do something terrifying.
In my opinion, this is a load of cow droppings but it is entertaining nonetheless.
Here is a link
The only makcik I fear is the one who can issue out summons