I drank a co-worker's coke from the office fridge
Oh dear, why did you drink someone else's coke?
I drank it because I was thirsty after lunch.
You shouldn't steal other people's things at work. You could get reported then eventually fired if you continue.
Who will I get fired? I don't care I won't be fired because no one cares
Well, your co-worker probably cares. If you get thirsty after lunch you should start bringing in your own drinks instead of stealing them from your co-workers.