Bf peeing in the shower

So I walked in the bathroom and saw my boyfriend peeing in the shower. He wasn’t taking a shower- he was standing on the outside and using the tub as a toilet instead of turning around to use the actual toilet. He said he was tired (it was the middle of the night for him) and didn’t feel like aiming. I’m so grossed out! Do guys normally do this? Why not just sit down and pee if that is a problem?