Most people just call out sick and 99.9% of the times you know in the back of your mind that your boss doesn't believe you but he has to accept the excuse anyway. Some companies take it as far as making you prove it with a doctor's note. So if you don't want to go through all that hassle, then simply plan your fake sick day off.
Most people don't do it that way. They just don't feel like coming in so they call that day.
Simple. Show up on time the day prior, and Pretend you're sick. Complain about something. Ask your boss “you have an recommendations for acid reflux? I feel terrible and it's creeping up all day. I don't know what it is”
When you clock out. Text your boss 1hr later. “Hey heads up…I took a turn for the worst, I'm vomiting…and not sure how this will play out tomorrow but I will let you know”
It sets the stage. Sometimes the boss will even tell you to take off. Usually “listen, it's ok. Take off tomorrow feel better”
That way even if they needed a note, likey they won't ask for one, and the result is your boss still thinking you're a stand up employee for showing up to work not feeling well. Meanwhile you have a day to yourself to do whatever you want.
Bosses are smart. Nobody feels amazing going to sleep, then wakes up with a full viral load vomiting everywhere with 102fever. No. It creeps up. Symptoms start then you take a turn for the worst.
One time I had a boss pay me for the day anyway without taking a sick day.
So do that. Set the stage. Give them the illusion you're honest.