There are five different situations that force a different version of "khalas" out of you every time. Khalas (I'll stop talking) ... here they are: 

1. When you've just had enough

It all starts with "tab ... ma khalas." 

When this khalas comes into play ... you know the war has just begun. It starts off with an extremely calm "kha" ... but soon escalates in both tone and volume when you get to the "las" part. 

This is the word you'll hear after you've asked someone a question more than 10 times in 10 minutes. It's really just another way of politely telling someone to shut up.

2. "Khalaset" ... when you've finished something

This one is basically a twist on the traditional khalas. It usually comes after an exhausting amount of time spent on doing one particular thing ... because you want it to be perfect. 

Mission accomplished! 

3. When you run out of points to back your argument

This is basically an agree-to-disagree kind of khalas. It usually happens when you've been in an argument with someone for over half hour and it seems to be going no where. Your argument loses its value, and khalas. You just want to move on. 

So you just try to make the other person happy and you say:  "Tab OK, khalas." 

4. If he betrays my trust, then "khalas"

This khalas marks the end of something, usually something big, huge, enormous. 

It's basically another way of saying there's nothing in the world that will change your mind about something if xyz happens. 

5. When you desperately want something to stop

Ya alllahh 3anjad khalas! 

This is usually the kind of khalas you say repeatedly in your mind when something annoying is happening around you. 

For example, someone in your building decided to renovate their house. On a Saturday morning, the workers begin drilling and moving things around at 7:30 am ... while you're sleeping. 

This is when you start talking to yourself as a thousand "khalas" come raging out of your mouth.