I know how to throw up on command and have been using it to get out of work
Why would you fake vomiting to get out of work? How can you even do that?
I will stick my finger down my throat and forcefully throw it back.
I do not think it is healthy for you to purposefully make you vomit as that can lead into serious injuries. I do hope you stop faking sickness and focus on your work, or maybe try to get a new job if you constantly want to quit your current one. I do not think it is fair for your manager or your coworkers to always excuse you if you're just faking.
It's fine and my manager doesn't care.
Even if he doesn't care, what you're doing is a form of deceit, and deceiving people is not a good trait. If your manager finds out, you may be fired and you may end up not having a job and you may not even get your manager's recommendation if you look for other jobs in the future.