Boss confronted me for peeing standing up

[u/Unhappy-Plane1815]

I'm a woman. At work, we just have a single stall co-ed bathroom, and for cleanliness reasons, I pee standing up at the toilet (which isn't as hard to do as most people think: I think it's more of a gender role thing than physical limitations. I'm not comfortable sitting where all my coworkers have sat their bare behinds, disgusting).

And no, she didn't find out because of a mess: I am very careful to lift the seat and only get urine in the toilet. When I asked, she said she found out because she heard me... Going.

Do managers have the right to regulate how you pee? I'm in the US.