Should i tell my parents about this?or what should i do?

My parents work during day and we are out for sumer. I was doing my chore list and was putting clothes up in dryer. Some were my brother's and i go to his room to give them to him. I knock on door he says come in, i open door and he is nude laying on bed watching tv. i just drop clothes and shut door. I didn't tell anyone, but today he walked out of the bathroom naked got his cell phone out of living room and back to bathroom. He would never do this with my parents home, I haven't told my parents cause it'd be weird and akward. I asked him why did you do that, all he did was laugh. Should i tell my parents, it'd be akward? or how do i get him to stop if he does it again? is he a pervert?