I'm going to stand up in my class and go to the bathroom
Is your teacher okay with you leaving class to use the bathroom during a session?
No.  I'm standing up and going to the bathroom at the same time.
You really shouldn't be making a mess of yourself like that, especially around so many people. Not only will you be made fun of by your peers, but the janitors will have to clean up your mess
Why? It's my business and I wanted to try it.
I don't really know why you would want to try this, but this isn't just your business.  You will offend the people in class, leave a mess for the maintenance staff, and may even cause the school to consider disciplinary action.  If this desire is too much for you to resist, at least try it in the privacy of your own home.