facking knackered - You're so tired you could sleep for a week and still not be

You're so tired you could sleep for a week and still not be ready for the day.

I woke up at 6 AM and had to go to school. I'm facking knackered.

I did 10 push-ups and a dance routine. I'm facking knackered.

I had to take a test and write an essay. I'm facking knackered.