I'm thinking of faking being half deaf at work so I could use that as an excuse for anything I did wrong or did not do at all
That sounds insane. Why would you think faking deafness is okay?
I love being able to get out of anything
Faking a disability to get out of work is terrible. It's rude to people with real disabilities and it's unfair to your co-workers. Plus if your boss finds out, you'll surely be fired.
It's unfair to fire me since I'm doing an important job.
If your job is very important, don't you think you need to take it seriously important as well? Faking deafness is not very kind to the actual disabled, and can put a bad image on you. How about just working hard and earning PTO and vacation so you can enjoy time off legitimately?