Whats "non-negotiable" mean?

"It means I´m not going to change my position. It´s fixed. May I remind you that this house is not a democracy? I am the boss here and what I say goes."
"Dad´s the boss," confirmed Peter, pointing me out to Jonathan.
"That´s right. Now just come here and ... Peter! Peter, come back here. You weren´t going to tell your mother that thing about me being the boss, were you?"

"Do not loose this house, Pel. I´m warning you. If we don´t get this house you will never have sex again."
"That´s rational. Buy a building or never have sex with you again."
"You´re not listening. I didn´t say "with me".
Mil Millington "things my girlfriend and I have argued about"